mauser chambering nightmare!

[bryan46964]

Well let me start by saying I hope that I am posting in the correct place, I am having a problem finish reaming my short chambered .300 win mag mauser barrel.. I was very cautious to not take too much out while reaming, talking about removing a half turn on the reamer then cleaning the chamber and checking with go gauge, just as the bolt starts to close on the go gauge I say to myself, "hey let's try the no go gauge" sure as hell the bolt closes..so crap I try the go gauge and still feel as if its tight, obviously I stopped at this point with reaming. It chambered rounds with force on the bolt as if it was still needing a few thousands removed, I test fired 10 rounds leaving the brass swelled up at the belting, I am starting to wonder if some how the chamber is oblong.. I was very careful not saying that I could not have done something wrong I just never came across this before after chambering a good amount of mausers in the past. Any help is appreciated ... action is a m48 large ring receiver, barrel is a shilen.

 

[Cypress]

Try and figure out if the ammo is hitting on the shoulder when chambering. If the chamber is too short in the shoulder then your round may not be seating properly at the belt area which is where the belted mag headspaces. I would probably take a little more out till your go fits then try the ammo again. If you've oblonged it then you'll be putting on a lathe anyway so it shouldn't hurt to try. I'm sure someone will be along shortly with better info...Thats the best I can do at 2 AM!

 

[Trent]

Cypress, my understanding is 300 Win Mag doesn't headspace on the belt. Headspace is off the shoulder.

Some other belted magnums headspace off the belt, but not 300 Win Mag.

So the bolt will close fine on a no-go, but is tight on on a go? This doesn't make sense.

 

[bryan46964]

I appreciate the responses .. I am seriously lost on this one, I think its going to be headed to the lathe.

 

[powell&hyde]

For people that shoot belted ammo, the very first time you shoot it in your rifle, the headspace is on the belt. This is true on all belted cases or ammo.
When resizing the empty brass after it was fired in your gun, use a neck sizer only, than when shooting the reloaded shells in the same gun will headspace on the shoulder and not the belt. It will give more life to the brass.

If you do a full length resize, your back to headspacing on the belt.

It doesn't make any sense at all that the bolt will close on a no-go but is hard on a go guage,

 

[rcmodel]

Any chance you could find another belted magnum rifle in any caliber to try the gages in?

It might be possible they were mis-marked by the company that made them.

rc

 

[NCsmitty]

I test fired 10 rounds leaving the brass swelled up at the belting,

That part would concern me the most, if it is actually ballooning the case. With no pics, it's hard to determine the situation.

Are you making the "safety breech" cuts as in the original design?


NCsmitty

 

[triggerman770]

chambering

the go gauge is about .004-.005 shorter than the no-go depending on the manufacturer. any chance you got them mixed up when trying(it can happen)
as to the brass swelling, I'd do a chamber cast with cerrosafe. Then you could mic it to be sure. you could also compare the casting to the gauges.

 

[bryan46964]

Now being that I am not the expert gun smith can someone enlighten me on the "safety breech" I have never had to deal with that on any of the k98k I am reading about this being only on the m48 hugo actions, I bought this action minus original barrel, im kind of lost here...cerrosafe is on order I really appreciate the input I will keep everyone posted...

 

[dirtyjim]

if your swelling the brass you more than likely cut the chamber oversize by putting side pressure on the reamer.
as far as the bolt closing on the no-go and not closing on the go gauge i would at least check the gauges against each other with a mic. or caliper.
are both gauges from the same manufacture?

 

[bryan46964]

I just measured the gauges they are same manufacturer and they are IDENTICAL SIZE..jim I just measured the chamber best as possible and I am seeing a .003 difference wow.. apparently I am retarted so looks like ill turn the barrel down and start over with less force...I feel like a idiot...

 

[Trent]

Nah, you aren't an idiot, just gaining experience the hard way, through trial and error. A lot of the knowledge I've obtained over the years has been due to screwing something up.

 

[NCsmitty]

Here's a link to rebarreling a M48 with the "safety breech" projection to fit the inner "C" torque ring and also picture of an original M48 barrel with all the cuts.

http://mausercentral.com/forum/viewtopic.php?t=18807

The way around performing a Safety Breech is to remove (grind) the projections on the ejector side, on the M48 bolt, or use a M1903 Turk Mauser bolt and then install the barrel like a normal M98 against the torque ring. The SB procedure created more case head support than a standard M98 Mauser setup.

Google a search if you need more info.


NCsmitty

 

[bryan46964]

Thank you NCsmitty, live and learn for sure! Thank you guys again for all the help.

 

[Jim K]

While belted magnum cartridges can be set up to fill the chamber and reduce shoulder expansion for longer case life in reloading, those rounds ARE INTENDED to be supported (headspace) on the belt. That is the reason for the belt, not the false idea that it "strengthens" the case, which it doesn't. It all started with the .300 and .375 H&H Magnum cases; the former has a shallow shoulder and the latter even less, so it was nearly impossible to get adequate case support until someone hit on the idea of the belt, which provides most of the advantages of a rim but makes the cartridge easier to feed.

Neck sizing only and not setting the shoulder back, will allow greater case life, since the shoulder brass is not being worked as much. BUT not setting the shoulder back will NOT "correct" a headspace problem. If the rifle has incorrect headspace (the distance from the bolt face to the front of the belt is too great), the cartridge will still stretch, just like a rimmed case will do with too much headspace, and break at the front of the belt.

Jim

 

[fguffey]

I was not there, In the beginning there was the rim, then the 7/57 type case, then there was the British, the ones with the 303 in the OFS against the Mauser, Kipling and C. Doyle returned from Africa knowing nothing was going to improve with the 303, so, they started a program to train their shooters to shoot better, then the soldiers were sent to France, to shoot the 303, about now it should not be difficult to convince anyone the British were resistance to change. To the British it was of little concern what happened to the case ahead of the rim, the rim’s purpose was to hold the case to the rear, then came H&H, with little concern as to what happened to the 375 H&H and the 300 H&H ahead of the belt, their only concern was the belt, the belt held the case to the rear, what happened to the case body when fired was of little to no concern, resistance to change, when the shoulder was improved/modified it became difficult to hit both at the same time (belt and shoulder), and again it was of little concern, the belt held the case to the rear and case body, when fired, took care of itself.

F. Guffey

 

[Clark]

Put Dichem or Magic Marker or something on a live round and chamber it a few times, and see where the paint gets rubbed off.

Put dial calipers on a fired round and measure around to see if there is any diameter run out.

I don't use a commercial go gauge. Belted magnum headspace gauges are a hair over .220" from the breech to the end of the belt.
Most brass is less than .215".
I headspace the rifle to be just big enough to fit the biggest brass my will ever use.
I have a large collection of brands and vintages of belted magnum brass, and the SAAMI specs that drive the go gauge size are too lose.

The other Mauser to magnum stuff to do:
Opening up the Mauser feed ramp.. must be done right. Use Walsh drawing.
Opening up the Mauser bolt face.. interrupted cut of hardened steel
Relieve the extractor... must be done right.

 

[BBBBill]

...Opening up the Mauser feed ramp.. must be done right. Use Walsh drawing...

OK, I did a search with no luck. Where would one find the "Walsh drawing"?

 

[Clark]

In the book on Mauser sporterizing by Walsh.
http://www.amazon.com/Mauser-M98-M96-Ronald-Walsh/dp/187935652X

I will send it to you.

It looks like that is an original drawing by Walsh, the old chief engineer, even if he got the info someplace else.

 

[bryan46964]

Clark thank you much for the drawing of the floor plate and all the info! I turned down my barrel about a hour ago waiting on new a new reamer I will try sizing to the brass! Keep you guys posted.. -bryan

 

[Trent]

If the rifle has incorrect headspace (the distance from the bolt face to the front of the belt is too great), the cartridge will still stretch, just like a rimmed case will do with too much headspace, and break at the front of the belt.

Jim

Question; if the case head separates at the belt, instead of somewhere further in the mid-chamber (typical broken shell), this is far worse for the shooter, correct?

Or does the point of separation not matter, to the severity of the damage it causes?

Just curious.

 

[fguffey]

Case head seperation

repeat:

I was not there, In the beginning there was the rim, then the 7/57 type case, then there was the British, the ones with the 303 in the OFS against the Mauser, Kipling and C. Doyle returned from Africa knowing nothing was going to improve with the 303, so, they started a program to train their shooters to shoot better, then the soldiers were sent to France, to shoot the 303, about now it should not be difficult to convince anyone the British were resistance to change. To the British it was of little concern what happened to the case ahead of the rim, the rim’s purpose was to hold the case to the rear, then came H&H, with little concern as to what happened to the 375 H&H and the 300 H&H ahead of the belt, their only concern was the belt, the belt held the case to the rear, what happened to the case body when fired was of little to no concern, resistance to change, when the shoulder was improved/modified it became difficult to hit both at the same time (belt and shoulder), and again it was of little concern, the belt held the case to the rear and case body, when fired, took care of itself.

F. Guffey

Then, about this time someone quotes hatcher, Hatcher with .080 thousands head space, me with .127 thousands head space, Hatcher was correct, he could not figure why his experiment failed, a couple of friends built 4 wildcats, magnificent wildcats using the 03 type receiver, 5 of the first 10 cases had case head separation with less head space than Hatcher, and I told them I could have told them 'IT' was going to happen, I told them had I been at the range I could have corrected the problem long enough to form their cases, and they told me they were going to form first then fire, and I thought that was nice.

 

[NCsmitty]

The M48 action is an intermediate length Mauser action, and I'm wondering how you are going to fit a 300 Win Mag cartridge in the magazine without extensive mag alteration. It's difficult enough to get an 30'06 length round to function through a M48, let alone a case that's about .150" longer than that.
A standard length LR Mauser would be better suited to this conversion, unless you use the M48 as a singleshot, or plan on seating the bullets deep into the powder space.



NCsmitty

 

[Clark]

NCsmitty
The M48 action is an intermediate length Mauser action, and I'm wondering how you are going to fit a 300 Win Mag cartridge in the magazine without extensive mag alteration. It's difficult enough to get an 30'06 length round to function through a M48, let alone a case that's about .150" longer than that.
A standard length LR Mauser would be better suited to this conversion, unless you use the M48 as a singleshot, or plan on seating the bullets deep into the powder space.

The max length for 30-06 is 3.34"
The max length for 300WM is 3.34"

My VZ24 I converted to 7mmRM only holds 3 in the magazine with a 30-06 aftermarket bottom metal by PAWS.
http://www.brownells.com/.aspx/pid=9718/Product/MAUSER-98-TRIGGERGUARD-FLOORPLATE

 

[NCsmitty]

The max length for 30-06 is 3.34"
The max length for 300WM is 3.34"

My VZ24 I converted to 7mmRM only holds 3 in the magazine with a 30-06 aftermarket bottom metal by PAWS.

The VZ-24 is a full length action, and that stock bottom metal will not fit an intermediate action like the M48 or the 24/47. The CTC of the M48 action screws are 7 5/8".
I reiterate, fitting a 300 Win mag in a M48 action will be quite a project for anyone but an experienced and/or determined machinist. A full length action like the VZ-24, which I have myself, would be a much better choice. That's all I got to say on that.


NCsmitty