1895 Chilean Mauser?

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kwheel

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I hope this isn't too much of a repeat question but I feel I have to ask because the interwebs searching I've done has pulled up some what conflicting information.

I have a sporterized 1895 Chilean Mauser (7x57) that appears to be in good shape. A couple gunsmiths have looked at it, to evaluate for mounting a scope, and said it looked to be in good usable condition.

After receiving positive feedback I purchased a box of Federal 175gr RN Powershoks (supposed to produce 2390fps at the muzzle) and took it to the range to see how it would shoot. I ran 10 rounds through it and other than a really quick glance at the cases for extreme indications of failure I didn't examine them closely. Other than it shooting high right the rifle performed well so I decided I'd reload for it instead of purchasing factory ammo.

Just recently I began to collect the needed tools and thought I should look closer at those cases to make sure they were in good shape.
I found that the primers had backed out ~.015" on every one of them and there was soot down the outside of the neck to ~1/8" above the shoulder, no soot anywhere else on the cases. All 10 look exactly like this.
Being the person I am I researched to see if this rifle had an issue that would cost a lot to fix and ran across a bunch of ideas about headspace and how important it is/or not, so I performed a few rudimentary measurements using techniques described in various posts.

I used an unfired Federal cartridge, cocked the bolt and put it on the middle safety that locks the pin but allows the bolt to cycle.
I used regular masking tape to create a headspace gauge by putting layers of it on the base of the cartridge, 1 layer the bolt closed easily, 2 layers the bolt rotated ~1/3 the way and stopped (probably could've forced it here but didn't), 3 layers the bolt would not rotate at all. My dial caliper measures this stack of tape (3 layers) at .017"

I compared the fired brass to a non-fired round, the necks are expanded to the point a bullet easily slides in, the case lengths are the same (within the tolerances of my dial caliper), the fired brass is .47" wide ~.3" from the base of the case, a non-fired round is .465" at the same point. This point is the widest point on the fired brass, the widest point on the non-fired brass is just above the extractor rim (not sure what the technical name is). This part of the fired cases is bright and shiny like the unfired cartridge.

The bolt face is in great shape, no pitting or erosion is evident, it's completely flat.

So, given what I've described am I dealing with a simple case of low power rounds pushing the primers out a bit or a rifle worn to the point where it needs new parts?
I bought it from my son who purchased it from a private party so we don't know it's history.
It's had a fair amount of work done to it, the stock is a nicer one from Boyds I believe and its been bedded to the action. The bolt has been turned down in preparation for adding a scope but the receiver has not been drilled and tapped nor has the safety lever been replaced.
The original sights were replaced with a modern ramped front sight and a fold down rear.

Aside from the stock being a lefty there is really not much else that needs any work, except maybe the chamber/barrel is worn out.

Thanks in advance for any input and I apologize if this is a topic that's been beat to death.
KWheel

P.S. I bought a box of Rifle Line (PPU) 139gr ammo and ran across a couple posts that hinted these rounds were too hot for the 95 Mauser actions, is this true?
 
It sounds like the throat is a little sloppy to me on the necks. That alone is not much to get excited about.
Get a candle and soot up the locking lugs on the bolt. Insert it and close it. Now pull it again and see if it looks like the bolt is locking up good or not. Most of the soot should be wiped off by the closing of the action. Soot it up again and push hard on the bolt handle while you close and open it this will give you an idea of the wear on the locking lugs and recesses.
If your excessive headspace is caused by wear there you can build up the locking lugs and fit them to the receiver or try another bolt if it's worth the effort and expense to you. If it's good and tight there you can just fire form your brass and either neck size only or dedicate a set of dies to this gun and adjust the sizing die up until it sizes them to suit your chamber.
Or you can pull the barrel and re cut the shoulder and chamber or rebarrel it and set the headspace correctly this time.
 
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#1Buck,
I used your technique and very little of the soot was wiped off the lug faces if I put no back pressure on the bolt while rotating it closed. I didn't mess with pushing it forward considering I was already seeing indications of problems.
I performed the steps you described with the bolt cocked and the safety lever in the center (lock the pin) position, I assume if I had the safety lever in the left position (off) the spring pressure would've caused the soot to be wiped off the lug faces. I did simulate that by pulling back on the bolt while closing it and yes, most of the soot was wiped off.

I then left the bolt as described (safety in the center position), put the bolt fully closed in battery and tried to pull/push it to see if I could manually detect slop, sure enough it moves enough that I can feel it and hear an audible click when it reaches the limit of travel in each direction.

I assume based on all this I should not fire it anymore and I have some decisions to make regarding whether I want to spend the money necessary to address the issues.

One of the gun smiths I had look at it made the comment that a lot of these old milsurp rifles are nothing but money pits, seems I may have one of those on my hands.
Fortunately I'm not into it a lot so there's no pressure to "keep going" and I have very little emotional attachment to it so passing it on to someone who wants to do what needs to be done is not an issue.

KWheel
 
So, given what I've described am I dealing with a simple case of low power rounds pushing the primers out a bit or a rifle worn to the point where it needs new parts?

Boatwright in his blog the well guided bullet calculated that it took 25,000 psia for the sidewalls of a 243 Win to stretch.

4.1 Elastic Stretching of the Case Head


After all portions of the brass walls that will ever yield have yielded into chamber contact, the steel walls of the chamber support the brass case walls very well. The stress situation within the case walls in this “excess headspace” situation of our example here then simplifies from three principal stresses being involved down to just a two-axis stress internally pushing the case head back toward contact with the bolt face:


Sr = -P(t),


St = 0


Sz = bk P(t).


So now the effective von Mises tensile stress here in the contacting brass case walls at the “0.280-inch point” becomes:


Seff = P(t) [1 + bk + b2k2]1/2 = P(t) [2.3560]


Once again setting Seff =59,200 psi, the estimated yield point where production of plastic strain can begin for the extra-hard brass of the case wall region around the “0.280-inch point,” and solving for this particular “secondary” axial yield pressure Pa:


Pa = (59,200 psi) / (2.3560) = 25,128 psi ≈ 25 ksi.


So, now we can begin to see how P. O. Ackley was able to get away with firing full-load .30-30 Winchester cartridges in an old Model 94 lever-action with its locking bolt removed. In our example FEA study, the case head first contacts the bolt face at a chamber pressure of about 25 ksi at 280 μsec, which (perhaps not coincidentally) happens also to be the chamber pressure at which the case walls will finally yield axially even with good radial support from the chamber walls


As all should know there is friction between the case and chamber and if the pressures are enough to lock the case in place, but not enough to stuff the primer back in the case (it is pressurized) and stretch the sidewalls, you will see phenomena like this:

JRQ7Ijz.jpg

P.O Ackley made a career out of one stunt with a M1894 action and a 30-30 case. You can see a re creation of what he did, and why it worked, and it had nothing to do with his theories that straightening out the case somehow lessened bolt thrust. It had to do with the fact that the pressures he was running was not enough to stretch the case sidewalls! P.O was such a operator.

Experimenting with Bolt Thrust https://gundigest.com/gear-ammo/ammunition/experimenting-with-bolt-thrust

Anyway, your M1895 was built in an era where the operating pressure of the service round was 43,000 psia, and the metallurgy of the era was primitive. Whenever steels of that era are tested, and I found papers on bridge steels from the 1880's/1890's to corroborate, the steels always have residual (tramp) elements, slag, impurities and are inferior in yield and ultimate compared to the exact same steels today. The exact same steels today are used in the cheapest applications, like rail road ties. No one who does not want to be sued out existence would use plain carbon steels in a firearms application. So what I am building to, is don't hot rod your ammunition to get the primers to seat.

I had a work bud who told me a story about shooting a sporterized Chilean M1895. I believe it was original barrel and receiver. Stock was different. It might have been scoped, don't remember exactly. He looked at the reloading data on the box, and said it was not hod rod reloads, he also checked the chamber to see nothing was plugging the chamber, and fired one round at the target. After firing the shot he noticed the top of the receiver ring was missing! It had blown off and luckily, not into his head. You are dealing with an action built before vacuum tube technology, before standardized testing. etc, etc, etc. Keep pressures low. These old guns were not built to withstand modern high pressure loads and the receiver seats can peen.

M0fMKHG.jpg
 
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Boatwright in his blog the well guided bullet calculated that it took 25,000 psia for the sidewalls of a 243 Win to stretch.

4.1 Elastic Stretching of the Case Head


After all portions of the brass walls that will ever yield have yielded into chamber contact, the steel walls of the chamber support the brass case walls very well. The stress situation within the case walls in this “excess headspace” situation of our example here then simplifies from three principal stresses being involved down to just a two-axis stress internally pushing the case head back toward contact with the bolt face:


Sr = -P(t),


St = 0


Sz = bk P(t).


So now the effective von Mises tensile stress here in the contacting brass case walls at the “0.280-inch point” becomes:


Seff = P(t) [1 + bk + b2k2]1/2 = P(t) [2.3560]


Once again setting Seff =59,200 psi, the estimated yield point where production of plastic strain can begin for the extra-hard brass of the case wall region around the “0.280-inch point,” and solving for this particular “secondary” axial yield pressure Pa:


Pa = (59,200 psi) / (2.3560) = 25,128 psi ≈ 25 ksi.


So, now we can begin to see how P. O. Ackley was able to get away with firing full-load .30-30 Winchester cartridges in an old Model 94 lever-action with its locking bolt removed. In our example FEA study, the case head first contacts the bolt face at a chamber pressure of about 25 ksi at 280 μsec, which (perhaps not coincidentally) happens also to be the chamber pressure at which the case walls will finally yield axially even with good radial support from the chamber walls


As all should know there is friction between the case and chamber and if the pressures are enough to lock the case in place, but not enough to stuff the primer back in the case (it is pressurized) and stretch the sidewalls, you will see phenomena like this:

View attachment 869450

P.O Ackley made a career out of one stunt with a M1894 action and a 30-30 case. You can see a re creation of what he did, and why it worked, and it had nothing to do with his theories that straightening out the case somehow lessened bolt thrust. It had to do with the fact that the pressures he was running was not enough to stretch the case sidewalls! P.O was such a operator.

Experimenting with Bolt Thrust https://gundigest.com/gear-ammo/ammunition/experimenting-with-bolt-thrust

Anyway, your M1895 was built in an era where the operating pressure of the service round was 43,000 psia, and the metallurgy of the era was primitive. Whenever steels of that era are tested, and I found papers on bridge steels from the 1880's/1890's to corroborate, the steels always have residual (tramp) elements, slag, impurities and are inferior in yield and ultimate compared to the exact same steels today. The exact same steels today are used in the cheapest applications, like rail road ties. No one who does not want to be sued out existence would use plain carbon steels in a firearms application. So what I am building to, is don't hot rod your ammunition to get the primers to seat.

I had a work bud who told me a story about shooting a sporterized Chilean M1895. I believe it was original barrel and receiver. Stock was different. It might have been scoped, don't remember exactly. He looked at the reloading data on the box, and said it was not hod rod reloads, he also checked the chamber to see nothing was plugging the chamber, and fired one round at the target. After firing the shot he noticed the top of the receiver ring was missing! It had blown off and luckily, not into his head. You are dealing with an action built before vacuum tube technology, before standardized testing. etc, etc, etc. Keep pressures low. These old guns were not built to withstand modern high pressure loads and the receiver seats can peen.

View attachment 869451
Slamfire,
If I'm reading your post correctly you're saying the ammo I ran through my old Mauser, Federal PowerShok, produced upwards of 59K psi to deform the cases as I described, am I correct?
If this is true then those rounds were loaded to a point where they produced ~50.7K CUP which is well above the industry standard of 46K maximum to accommodate old guns like mine.

BTW: I really appreciate all the info and the included math!! My spent 7x57 cases (primers and case walls) look virtually identical to the 30-06 cases you show in the picture. The primers are protruding about the same and the bulge in the case walls is in the same place and about the same magnitude.

I got to thinking a bit more about the soot tests I performed so I examined the bolt on my Remington Model 700, it's even looser than the Mauser's when no round is chambered so I'm skeptical tests indicate anything useful.

Edit: I checked the Remington again and the bolt was not completely closed when I found it was sloppy.

KWheel
 
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Kwheel your best bet in this case to make it shootable is to pull the barrel and either rebarrel it with a new short chambered barrel or recut the shoulder on the barrel and cut the barrel face back where the sights still clock right and the chamber is short. Once you get the short barrel back in place you recut the chamber with a reamer and the headspace problem is cured. As stated above I'd keep it to mild loads.
You could also build up the back of the back of the locking lugs and fit them.
The cheaper alternative is to part it out and sell it to someone who wants to build themselves a custom rifle. I'd pull the barrel so that whoever fires it next has the smarts to put it back together and assumes that liability.
There's an off chance that another bolt that is not as worn may headspace correctly. You can mic the lugs and get some parts sources to check theirs before you buy if you call them and explain the situation.
 
#1buck is correct that you can requalify the old barrel by setting it back but the cost for gunsmithing might be more than it is worth and the barrel's rifling will not rejuvenate.

Regarding the ammo, the Powershock is close enough in specs in speed and bullet weight to the military issue round that it probably was not that hot ammo as Federal does not want to "blow up" someone's antique firearm. You can always call them and ask them yourself about advice. The Prvi is slightly hotter as far ft lbs go but the real risk is that it may use a different powder demonstrating a pressure spike and recoil impulse that might adversely affect the rifle's integrity. Some rifles have blown up with blanks but fired regular ammo ok. Blank powder is some of the fastest and nastiest stuff on the market and should never be used with any bullet. If you think of rifle steel as like a crystal goblet where some frequencies can cause shattering while others leave it unaffected, you get the idea.

First, I would check it your self with a true headspace gage--a field gage is the absolute maximum but given you want to fire commercial ammo, then the no-go would be preferable. Grafs and sons is a good place as is Midway to buy one and there are two rental reamer outfits that will rent them to you. The two gages would run about 30 each.

A few folks that want to take the risk can fireform cases (making a wildcat essentially) to the new larger chamber and reload these cases for only that rifle if the headspace is between no-go and field gages. Brass life is shorter (sometimes only a single firing after fireforming) but with prudent lower pressure reloading, often with cast bullets, some folks go ahead and shoot them despite a risk for cartridge separation. Another risk is that metal fatigue, even on a lower pressure round, coupled with a different peak pressure from a different powder might just cut loose so someone would have to be scrupulously alert if firing such especially if a gas event happens.

Another possibility, assuming no lug setback in the receiver such as demonstrated above by Slamfire, would be to buy a new small ring sporter barrel--Brownells used to have these for around $100 that are short chambered and Midway did have something similar at one time. These are good enough for sporter use in an old rifle.

Building up the locking lugs is really not practical on old Mausers as you would have to re-heat treat the receiver after doing so and sometimes even the best of folks can warp the receiver beyond repair doing so. These are plain carbon steel and surface hardened which is not conducive to cheap fixes. One cannot really lap the lugs very much to fit either as these bolts are case hardened too and the layer of case hardening is thin and can be inconsistent even when new.

Regarding bolts for these, there might be a rare NOS bolt floating around but it will be pricey. Even used m95 Mauser bolts are bringing well over $100 when you can find one like fleabay. When Samco Global went bust, a huge wave of 93 Mausers hit the market and a lot of folks went looking for bolts. Well the 95 bolt fits the 93 action but vice versa is not true so some folks preferred the 95 bolts in their 93 Sporters for feeding issues. Thus, a shortage of m95 Mauser round bolts and Swede Mausers bolts will not work as they are different specs.

Mausers have one not so nice flaw in that they do not give great support to the cartridge's rear if they are out of headspace risking cartridge separation or worse. You do not want hot gas coming at you or the receiver in an antique firearm.
 
Thanks for all the help guys.
I've pretty much decided this particular Mauser is either going to be a wall hanger or get passed on to someone who can fix it correctly and is willing to spend the time and money to do it.

KWheel
 
Thanks for all the help guys.
I've pretty much decided this particular Mauser is either going to be a wall hanger or get passed on to someone who can fix it correctly and is willing to spend the time and money to do it.

KWheel
I also hate to suggest it but you could part it out as the rifle as you describe is not really in a firing state so there is always a risk that someone purchasing the rifle does something unwise with it which could be problematic. The dilemma is that right now it is not really collectible as it is not in issued condition (a completist collector will buy a rifle unsafe to fire just to have one to fondle) and it is not useful as a sporter rifle as it would be unsafe to fire.

Thus, scavenging it for parts to sell might be the better option than selling it outright unless you do not want the hassle. In the latter case, I would consider maybe selling to a collector website that also does parts such as Liberty Tree Collectors, Simpsons Ltd., Old Western Scrounger, and a few others but you will take a hit on profits due to shipping, handling, and their profit margins. GPC for example was notorious for paying gunsmiths scrap metal prices for bits and bobs of parts and then reselling them substantially higher. In fairness, they have to sort and catalog boxes of "stuff" and some of the stuff would be scrap. Another possible way is simply sell the bolt separately as these are getting rarer and then the rest of the rifle as a gunsmith special which puts the onus on the future buyers to fit a new bolt to it.
 
My gunsmith would probably get around $100 to either rebarrel or to cut the shoulder back. I love the 7x57 cartridge so I would stay with it. But if you want something different the .250 or .300 Savage both run at 46,000 cup max chamber pressure and fit that action nicely. The .257 Roberts is a great cartridge that is a necked down 7x57 but there are two tiers of reloading data. The standard data keeps it safe for the older guns as does factory loaded ammo from Federal, Winchester, and Remington. There is what they call .257 Roberts+P for modern guns like T/C Contenders, Winchester Model 70s and such. Stay away from those loads in that gun. The 7x57 is rated at 48,000 cup so any cartridge below what would be ok. As an added precaution I wouldn't push the maximum in those cartridges in an old gun anyway.
What you have is a good base for that lightweight, mild recoiling hunting rifle you always dreamed of.
 
#1Buck,
Yeah, this whole thing has me a bit conflicted.
I like how the rifle behaved at the range, decent groups (for old eyes with open sights) and light recoil, not to mention it wasn't the typical AR platform everyone else was shooting that day.
(I'm a bit of a contrarian so the "popular" thing turns me off).
Problem is, it needs more work that just dealing with the safety issues to be really usable for me.
The stock is a lefty, I'm very right handed, so I need to either replace it or modify it to be ambidexstrous, the open sights are hard for my old eyes to see well so I planned to put an aperture sight on it.
Now I'm leaning towards a modern rifle so I don't have the concern of the condition of the action nagging at me in the back of my mind.
I'd like to stick with the 7x57 if I can, maybe find a Ruger 77, Remington 700 or something similar chambered in it.

I planned to reload, even have a set of RCBS 7x57 dies I bought from a co-worker years ago for this rifle, gave a whole $10.00 for them.
Ah well, such is life!!
I suppose I should take it to a local gun smith and have them do real examination of it, make sure all the warts are known before deciding on a course of action.
KWheel
 
Your gunsmith may be able to build up the locking lugs as I stated above and fit them. I threw a lot of options at you though. Then I bet the headspace will be in spec.
 
Providing there is no lug set back, a cheap way, is to form some 30-06 to just close and shoot away. The thicker neck shouldn’t be an issue.
 
Your gunsmith may be able to build up the locking lugs as I stated above and fit them. I threw a lot of options at you though. Then I bet the headspace will be in spec.
Using a dial indicator I measured the longitudinal movement of the bolt when closed on an empty chamber and got .006".
Using that and the .015" protrusion of the primers I get a headspace distance of .009" with the Federal cartridges assuming the bolt lugs could be built up to eliminate the longitudinal movement.
So, where does that leave us?
I'm too new at this to have much of a feel for whether .009" is something to be concerned about.

Providing there is no lug set back, a cheap way, is to form some 30-06 to just close and shoot away. The thicker neck shouldn’t be an issue.
If I understand this, assuming there is no set back which hasn't been determined yet, doing this creates a custom cartridge specifically sized for this rifle, correct?
I'd not want to use factory ammo again, buy or somehow acquire 30-06 brass (2 of my other rifles are 06 so not a real issue) and load light as I would anyway, again, is that correct?

Boom Boom, #1Buck and Slamfire,
What do you guys think of the idea of forming 06 brass for use in this Mauser?
I did some calling around today and it seems there's one local gunsmith that might have the correct headspace gauges but those won't say anything about lug setback will they?
If not, how can lug setback be measured or did I do that with my dial indicator? :)

KWheel
 
Slamfire,
If I'm reading your post correctly you're saying the ammo I ran through my old Mauser, Federal PowerShok, produced upwards of 59K psi to deform the cases as I described, am I correct?
If this is true then those rounds were loaded to a point where they produced ~50.7K CUP which is well above the industry standard of 46K maximum to accommodate old guns like mine.

Do you ever quote stuff you don't fully understand even though you think you understand it and fully comprehend? Well, I do it all the time! :oops: And this was an example and I had to go back and re-read James A. Boatright's Yielding of Brass Case Walls in the Chamber.

Now, I could still be getting this wrong, :eek:

Pl0HbjY.jpg

but the value of 59,200 used by Professor Boatright is the yield strength of ultra hard brass. Cartridge brass hardness varies by location, the case mouth is softer than the case head, and Professor Boatright, in this calculation, is using 59,200 pounds per square inch for the yield strength of brass in the case head area. He claims the case head does not expand into the chamber, and it is at this location where the sidewalls stretch to the bolt face. Now the first sections of the case to expand are the neck and shoulders, all made of thinner brass, and softer brass.

Now the important thing to understand about Professor Boatright's calculation is that while ultra hard brass may have a yield strength of 59,200 psia, cartridge cases are not one inch thick! Based on his estimate where case heads stretch, the case wall thickness is 0.045 inches.

So, given case sidewall thickness of 0.045 inches, you would expect the sidewalls would start to stretch given an internal case pressure of 25,000 psia.

His stress calculation is based on a Von Mises stress model, which incidentally, your Chilean Mauser was built before the Von Mises ductile model existed! At best Mauser was using a simple shear model when he calculated the thicknesses of the bolt lugs and receiver seats. The hot rod clan has no idea of the history of technology and just how primitive manufacturing technology and mechanical analysis was in the 1890's.

I also looked at the SAAMI specs for the 7mm Mauser cartridge and for the 8mm Mauser cartridge. I don't know why the 7mm Mauser case is much higher than the 8 mm Mauser. I believe the maximum SAAMI pressure for the 8mm cartridge is 37,000 psia. I consider this acceptable as I know the early 8mm Mausers, and 7mm Mausers's, were built for a cartridge operating at 3000 atmospheres. Which is, 43,000 psia. There are lots of fan boys who want to hot rod these old actions, and making a case what exact pressures these things were operating is very contentious with the hot rod crowd. They want to increase pressures and cherry pick, or demand impossible proof, to justify their wants, desires, and risky behavior.

For the hot rod clan, I am positively hopeful for their ultimate success in the quest to blow their own fool heads off. But when dealing with old, vintage, metallurgy, I am going to dismiss their advice and be cautious with the operating pressures of these antique firearms. I absolutely recommend that anyone using period firearms not exceed the pressures of the original service cartridge which the action was originally built to support. And if the action was converted to a different cartridge, than the bolt thrust of the new cartridge should not exceed the bolt thrust of the original cartridge.

To beat this further, there is absolutely, positively no evidence that the Military action manufacturer used a higher grade of steel, or altered the heat treatment of their actions, so their actions could be used in some future date with higher pressure ammunition than the service cartridge.
 
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Using a dial indicator I measured the longitudinal movement of the bolt when closed on an empty chamber and got .006".
Using that and the .015" protrusion of the primers I get a headspace distance of .009" with the Federal cartridges assuming the bolt lugs could be built up to eliminate the longitudinal movement.
So, where does that leave us?
I'm too new at this to have much of a feel for whether .009" is something to be concerned about.

You need chamber headspace gages to positively determine headspace. And, I am going to offer a new concept, one that is virtually ignored, and that cartridge case head protrusion is the more important, safety critical measurement.

This is the amount of case head that sticks out of a M98 barrel.

eUXibtK.jpg

More of the case head sticks out of 03 barrel.

mgWVePU.jpg

If you read Chinn's Vol IV The Machine Gun, a book everyone ought to read to understand the principals of action design and how central case head protrusion is for action design.

(these pictures come from Vol IV)

pWU3Rmi.jpg

At this point of case head exposure, the sidewalls blow:

2xGBYpt.jpg

Now the amount of forward clearance in the chamber, that is the distance from bolt face to chamber shoulder, a distance more or less called "headspace", is an important issue, a couple of reasons, too much can cause misfires or case head separations, but as long as the case head retains its integrity, the action won't blow.

I don't know how to measure case head protrusion with a gauge. If the action was properly built and nothing has changed since manufacture, case head protrusion should be OK. I will say, the assumption is, if headspace gauges indicate excessive headspace, then the lugs and recesses have peened and cartridge case protrusion has grown. And that is the assumption, and it is not a bad assumption when some worker has hundreds, if not thousands of rifles to safety check. The worker sticks a chamber headspace gauge in the gun, and if the bolt closes on the gauge, the weapon goes in the rebuild/reject pile.

But, it could be that your rifle has a deep chamber. That is not unknown in military rifles, the chamber could have been reamed a little deep for various reasons. And as long as cartridge case head protrusion was not increased, that would not be dangerous.

So before you do anything, is get chamber head space gauges and determine the real headspace of the action. And don't freak out about the clearance between bolt and breech face. Actions need a certain amount of clearance between the bolt and action, or dirt inside the receiver locking recesses will jam the action.

I had a paper staple jam my target AR15. Before going to a rifle match, I opened the bolt, inserted an open bolt indicator, put the rifle in a hard case, and took it to the match. Once on the firing line, I was unable to chamber the first round and I could not figure out why. The bolt was almost closed and nothing I could do would get the bolt to go into battery. I had to separate the upper and lower, in my shooting period, remove the bolt carrier, and found there was a small staple against the barrel end!. Paper staples are not that thick, but it was thick enough to jam the action keep the lugs from going into battery!. And I have no idea how that staple got into the case.
 
Do you ever quote stuff you don't fully understand even though you think you understand it and fully comprehend? Well, I do it all the time! :oops: And this was an example and I had to go back and re-read James A. Boatright's Yielding of Brass Case Walls in the Chamber.

Now, I could still be getting this wrong, :eek:

View attachment 869678

but the value of 59,200 used by Professor Boatright is the yield strength of ultra hard brass. Cartridge brass hardness varies by location, the case mouth is softer than the case head, and Professor Boatright, in this calculation, is using 59,200 pounds per square inch for the yield strength of brass in the case head area. He claims the case head does not expand into the chamber, and it is at this location where the sidewalls stretch to the bolt face. Now the first sections of the case to expand are the neck and shoulders, all made of thinner brass, and softer brass.

Now the important thing to understand about Professor Boatright's calculation is that while ultra hard brass may have a yield strength of 59,200 psia, cartridge cases are not one inch thick! Based on his estimate where case heads stretch, the case wall thickness is 0.045 inches.

So, given case sidewall thickness of 0.045 inches, you would expect the sidewalls would start to stretch given an internal case pressure of 25,000 psia.

His stress calculation is based on a Von Mises stress model, which incidentally, your Chilean Mauser was built before the Von Mises ductile model existed! At best Mauser was using a simple shear model when he calculated the thicknesses of the bolt lugs and receiver seats. The hot rod clan has no idea of the history of technology and just how primitive manufacturing technology and mechanical analysis was in the 1890's.

I also looked at the SAAMI specs for the 7mm Mauser cartridge and for the 8mm Mauser cartridge. I don't know why the 7mm Mauser case is much higher than the 8 mm Mauser. I believe the maximum SAAMI pressure for the 8mm cartridge is 37,000 psia. I consider this acceptable as I know the early 8mm Mausers, and 7mm Mausers's, were built for a cartridge operating at 3000 atmospheres. Which is, 43,000 psia. There are lots of fan boys who want to hot rod these old actions, and making a case what exact pressures these things were operating is very contentious with the hot rod crowd. They want to increase pressures and cherry pick, or demand impossible proof, to justify their wants, desires, and risky behavior.

For the hot rod clan, I am positively hopeful for their ultimate success in the quest to blow their own fool heads off. But when dealing with old, vintage, metallurgy, I am going to dismiss their advice and be cautious with the operating pressures of these antique firearms. I absolutely recommend that anyone using period firearms not exceed the pressures of the original service cartridge which the action was originally built to support. And if the action was converted to a different cartridge, than the bolt thrust of the new cartridge should not exceed the bolt thrust of the original cartridge.

To beat this further, there is absolutely, positively no evidence that the Military action manufacturer used a higher grade of steel, or altered the heat treatment of their actions, so their actions could be used in some future date with higher pressure ammunition than the service cartridge.
Got it!!
You weren't, or rather I should say Professor Boatright wasn't saying it took 59,200 psi to deform the case, instead that would start to happen at 25,000 psi given the soft thin brass a case is made from.

I have no intention of hotrodding any loads for this rifle, I just wanted a nice reliable, easy on the shoulder rifle I could leave in the truck. This is turning into much more of a quest than I really wanted to deal with.

KWheel
 
Got it!!
You weren't, or rather I should say Professor Boatright wasn't saying it took 59,200 psi to deform the case, instead that would start to happen at 25,000 psi given the soft thin brass a case is made from.

I have no intention of hotrodding any loads for this rifle, I just wanted a nice reliable, easy on the shoulder rifle I could leave in the truck. This is turning into much more of a quest than I really wanted to deal with.

KWheel

Look, you have fired twenty factory rounds, they performed well, and were so low pressure that you had backed out primers. I don't see a problem with any other that. The backed out primers were not a problem, you tried finding a problem with your headspace measurements and bolt drive in, and I don't think you have a problem with either of those.

So, go out and shoot some more factory ammunition, stay the heck away from old, dangerous surplus ammunition, just shoot nice, new US factory ammunition, zero the rifle, and all will be well.
 
kwheel, for piece of mind, if nothing else, check your headspace via buying or renting gauges or have a gunsmith do it with the proper gauges. A gunsmith can check for lug setback which generally causes a sticky bolt on extraction as the lug surfaces have plastic deformation. Depending on the length of your fingers, you can actually feel lug deformation as your fingers are incredibly sensitive--if short fingered, a dental angle mirror with light or a borescope can easily demonstrate such. Of course, removing the barrel is another way as the signs are obvious. If you neck size, you should be able to get maybe a reload at least once but it will require scrupulous checking of the brass for incipient cartridge separation after firing each time.

BTW, there is not a cheap nor easy way to fix lug setback due to the case hardening of the lug surfaces (plain carbon steel) and any welding, including TIG welding, will affect a key safety related surface of the firearm requiring re heat treatment of the whole receiver. Any welder undertaking such would be exposed to liability if someone went ahead and used the thing without going through the requisite additional steps such as re-heat treatment of the receiver, reproofing it, and probably magnafluxing the receiver to detect infirmities. Recently, a few places were selling m95 Chilean barrelled receivers for about $100 or so and a few folks sell one now and again on Gunbroker for maybe a bit more.

The old timey way to fix such a receiver, if someone wanted to do such a thing when they were cheap is to grind carefully the lug recess surfaces back to remove the deformation, reheat treat the receiver because the grinding will remove the case hardened surface, and then setback the barrel (or put a new one on) to adjust the headspace to what it needed. The 98 due to its locking ring versus the shoulder in small rings was a bit more complicated. The risk was that you could do all of that and still end up with a lemon if anything went wrong.

Welding up something introduces a whole nother problem because of the energy involved and the nature of the steel of an uncertain alloy being used. If the old timers were to weld anything, they would mess around with the bolt--the key is to always alter the cheapest part before the expensive irreplaceable ones. Building up a locking lug on a bolt would still require heat treatment though with the risk of bolt warpage.

I do not doubt that someone with motivation could do such a thing, but it will not be economic in the least and conceivably could ruin the receiver during re-heat treatment (warpage).
 
Now the amount of forward clearance in the chamber, that is the distance from bolt face to chamber shoulder, a distance more or less called "headspace", is an important issue, a couple of reasons, too much can cause misfires or case head separations, but as long as the case head retains its integrity, the action won't blow.

I don't know how to measure case head protrusion with a gauge. If the action was properly built and nothing has changed since manufacture, case head protrusion should be OK. I will say, the assumption is, if headspace gauges indicate excessive headspace, then the lugs and recesses have peened and cartridge case protrusion has grown. And that is the assumption, and it is not a bad assumption when some worker has hundreds, if not thousands of rifles to safety check. The worker sticks a chamber headspace gauge in the gun, and if the bolt closes on the gauge, the weapon goes in the rebuild/reject pile.

Slamfire, the classic way to check cartridge head protrusion is to remove the barrel and use a depth micrometer gauge, (an ordinary caliper gauge can get very close you are careful). Placing a headspace gage in the barrel, you measure with the depth gauge how much the head of the headspace gauge protrudes from the barrel. Then you check the distance from the locking shoulder of the barrel to the end of the barrel. These should agree plus the .002 crush tolerance on threads for torquing the barrel into the receiver.
 
Slamfire, the classic way to check cartridge head protrusion is to remove the barrel and use a depth micrometer gauge, (an ordinary caliper gauge can get very close you are careful). Placing a headspace gage in the barrel, you measure with the depth gauge how much the head of the headspace gauge protrudes from the barrel. Then you check the distance from the locking shoulder of the barrel to the end of the barrel. These should agree plus the .002 crush tolerance on threads for torquing the barrel into the receiver.

Excellent procedure! And a bit more than the OP probably wants to go through.
 
Excellent procedure! And a bit more than the OP probably wants to go through.

I can't claim credit for it as it is the std. gunsmithing procedure to do such when finish reaming a barrel for fitting by hand. You set back to shoulder on a Mauser barrel using comparable information derived from the receiver's locking surfaces which vary for the m98 versus the older Mauser models. The m98 headspaces off the C locking ring inside the receiver but a well made rifle will have the shoulder adjusted to just fit the receiver. The older Mausers fit on the shoulder for headspacing. Patrick Sweeney's Rifle Gunsmithing book and Gunsmithing Kinks series cover the particulars and have some information on other makes as well. Steve Wagner's Turk Mauser pages used to have this information as well but these are not online anymore from my understanding.

One of the reasons that I like to rebuild Oberndorf Mausers is that their measurement specs have always been exact while other makers tended to wander a bit. The Czech Mauser 98 receivers, for example, that I have seen are a bit deeper from the outside of the receiver ring to the internal locking ring than the Oberndorfs to the locking ring and that often requires shoulder adjustments on the barrel if it is not a Czech.

Oberndorf during WWII, as opposed to other factories, also never used slave labor that I can tell from history, faced little pressure from bombings, and there aren't reports of wartime heat treatment issues like some other makes. Even then, 1943 would be my cutoff date for a shooter rifle due to material shortages affecting composition. My Oberndorf receivers spec out to the same despite being made in midwar WWI, midwar WWII, and the preWWII era respectively. The Swede Mausers that I have do not show the same precision in manufacturing specs fwiw despite being receivers being made in roughly the same timeframe and without the pressures of war. The English, fwiw, in their Enfields also demonstrated a curious precision and good construction on parts that mattered but much less concern about exterior appearance and machining of parts that don't. They were also rather casual during wartime about bore sizing. The secret to British arms was their quality of handfitting and their Armorer specialists.
 
I found a local gunsmith that has headspace gauges for 7x57.
I hope to be able to get over to have him check this thing tomorrow (Nov 6th, 2019), then I'll let you guys know what we find.

KWheel
 
Well, I was able to make it to the gunsmith this morning.
He tried both the No-Go and the Field gauges, the action closed easily on both of them.
Unfortunately I was so disappointed I forgot to ask how much they'd charge to set the barrel back and ream the chamber, but at this point I'm just going to move it on to someone who wants to put the work into it.
If anyone here is interested let me know, maybe we can work something out.

Thanks for all the input and advice guys!!

KWheel
 
More of the case head sticks out of 03 barrel.

Not true; reloadrs do not measure case head protrusion, The Mauser case head protrusion is .105", and then there are the few that measure .110".

The 03 and 03A3 measure ? No one measures. If they die they would measure from the case head down the beginning of the extractor cut. For the few that have made that measurement they found the depth was .090".

The strength of the case head. When something went wrong with the 03 case head they called it catamorphic when a hole was blown in the case head at the extractor cut.

And that is the reason I have said military case heads are not as safe as Remington 30/06 case heads; in the old days because I have Remington 30/06 cases with case heads that are .260" when measured from the bottom of the cup above the web to the case head.. All of my military LC type case heads have a thickness of .200".

And then someone is going to say the military case is thicker because it is heavier; they never consider the case head thinner and the case body is thicker.

F. Guffey
 
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