Studying Bolt Action Designs

[sirgilligan]

I have been studying bolt action designs for a while. I really like the bolt action of my CZ 527. It is a Controlled Round Feed (CRF) type, a Mauser action with the ejector fixed to the receiver and it slides into a slot cut into the bolt that bi-sects on of the lugs.

I have found that the Ruger M77 Hawkeye has a CRF bolt, and they modified the cut out for the ejector so that it does not split a lug.

Of course there is the Rem 700 with the ejector that is a plunger / pin.

But my question is about the Mausingfield action from American Rifle Company (ARC).

Having the ejector like a 1903 Springfield seems to be very similar to the ejector in my CZ. So, the big point is the toroidal (donut) shape to the lugs, that can only settle to "one location" in the chamber. The CZ 527 bolt is not toroidal, but more a wedge, but if a wedge is mated properly to a chamber it can only go in and settle to one location as well, right? So, am I missing something about this new action made by ARC? I like it, but I don't see the donut feature making it that extraordinary. What am I missing?



Photo of my CZ 527 bolt. I learned a while back to photograph every new firearm I get before I shoot it.

 

[chicharrones]

I've never heard of toroidal, but your question made me look around and I found this.

http://precisionrifleblog.com/tag/surgeon-rifles/

 

[sirgilligan]

Yes, that is the bolt I was referring to.

Does anyone have one? Or maybe, someone that builds rifles might have some comment on it?

It seems reasonable, but not really different.
At $1400, I am looking for the advantage this action has, or the problem it solves, etc.

 

[cprher]

You are missing nothing

Cone into cone is by very nature very precise; however, the machining necessary to get a perfect fit is non-trivial. I believe, but certainly can't prove, that Mausingfield's toroidal locking lugs are something of a gimmick. A carefully fit bolt body is I think a better way to go. On my last Rem 700 project I went with an oversized Pacific Tool and Gauge bolt (.704") after having my action reamed to .705". The bolt now operates as if it were on ball bearings and closes like its part of an expensive safe. Once the lugs were lapped in the action was as good as or better than any action I've tried. Now, by the time I was done I'd spent as much as if I'd purchased a Surgeon action, but then I wouldn't have had the fun of building a truly superb rifle.

Keith

 

[Slamfire]

Following the definitions below, I consider the toroiod bolt claims to be Bull**** not Nonsense*. A exaggeration which, if it gets you to buy, is harmless. I do think someone buffed the Mauser bolt logs out of parallel as the lugs on my FN Mauser deluxe look straighter.

FN Mauser Action



The Bernard action uses three lugs. This action is a work of machining art, the lugs are properly machined so that there is perfect contact between the bolt lugs and the receiver seats. With three lugs, there is a lot more bearing in the receiver than with two, and that is a selling point for these actions.






How to Speak Money, Lanchester

Pg 86 bull**** versus nonsense

Nonsense is different: it’s worse. It consists of things that are actively false, and at its worst, of things that are just not true but can’t possibly be true. It is rarer than bull**** but much more toxic, and it is the difference between someone exaggerating a bit because he is trying to sell you something and someone who is consciously lying to you, or who is so far out of touch with reality that he does not know he’s lying.

 

[sirgilligan]

I am thinking the differentiating part for the Mausingfiled is that it is a CRF that has the same external dimension as a Rem 700 action and it has the Savage design for attaching the barrel.

 

[Jim Watson]

If they are so smart, why did they split the left lug for the ejector? Winchester quit that about 80 years ago.

 

[bush3755]

3- or 4-lug actions with squared up bolt faces shoot new cases most accurate.

Sloppy fit Winchester 70 action based match rifles are capable of accuracy equalling custom actions costing 5 times as much. And they're a lot stiffer than Remington 7XX ones. As long as the bolt closes into battery the same way for each shot, it doesn't matter how close fit their parts are. So says people who've proved it.

Mauser chose to design one function to open the bolt stop and clear the ejector. Ejecting empties straight to the sides means fewer distractions in rapid fire as there's less chance a hot empty ending up on the rifleman. And without an ejector slot in the bottom of the receiver, it's a little stiffer.

 

[barnbwt]

That toroidal stuff doesn't make any sense at all. Any shape machined as carefully as these high-end guns will repeat just fine. And besides, we have this extremely fancy alignment feature called the chamber on all our guns, so it's kinda moot if you have a snug match chamber. I also don't understand how a large two or three lug bolt can do anything but load up each of its lugs and align the bolt face like a stool under load, assuming machining quality is such that all lugs initially contact the recesses properly (a toroidal shape won't help either if one of the lugs is too far forward/back). The rounded lugs of the fancy action strike me the same as the rounded necks of the Weatherby's; pure branding.

"3- or 4-lug actions with squared up bolt faces shoot new cases most accurate."
Don't you start losing a degree of your positive initial extraction arc on those actions due to the shorter angle of rotational engagement, though? Especially for higher than 3 lugs.

TCB

 

[4v50 Gary]

Remington uses that spring type extractor for a reason: total enclosed cartridge.

In event of a case failure, the Remington bolt head is designed to expand, sealing against the barrel to prevent gases from escaping to the rear. That's why I don't care for the Sako type extractor on a Remington.

BTW, best books on the subject are Stuart Otteson's The Bolt Action Rifle Vol. I & II. It's available on DVD from Wolfe Publishing.

 

[briansmithwins]

I suspect a spring loaded extractor is cheaper to manufacture.

BSW

 

[sirgilligan]

A friend emailed me some pictures about a year ago of his CZ 527 that had experienced a case head failure. The shooter was injured, but not permanently so. I know there was a lawsuit with the ammo maker, so the details of the injury have never been disclosed to me, but I think there was maybe a burn because of gas coming out around the magazine, and some gas in the face that may have irritated the skin. The bolt held in place, it had to be beat out actually.

I think that this Mausingfield action is interesting, it has features I personally like, but I don't know about the price, because, when you make something special it has to be solving a problem or doing something better.

I think the better is the Rem 700 compatibility while retain the CRF. It might be better that it uses a Savage barrel nut system too, so you can change your own.

So, maybe it is worthy of some support by those that need those features. Just thinking out loud.

 

[MachIVshooter]

My thoughts have been pretty much covered above (its a gimmick), but I'll just nitpick one detail; their design is about as much a wedge shape as it is a torus.

Armalite did figure out a "better mousetrap", though, with the AR-50. 3-lug floating bolt head:

 

[taliv]

i'm not a fan of the springfield, mauser etc actions, so i don't care much for the mausingfield either. not saying it's bad, just takes a philosophically different approach than i have to solving problems

however, if you want to see a work of art, check out this thread, and particularly follow the facebook links and video. seriously impressive bit of gunsmithing, especially the stock and carbon fiber bedding

http://mbd.scout.com/mb.aspx?s=541&f=5522&t=13773471

this rifle was built as a prize to the snipershide cup winner

 

[Hookeye]

What about the Merkel Helix?

 

[sage5907]

When I buy a bolt action rifle I won't even look at a design that has a receiver that is round on the bottom like a 700 Remington. A far better design is the flat bottomed receivers of the Mauser and the Winchester 70, and I like both the Mauser commercial actions and the Winchester 70. The Mauser has a high speed lock time that is second to none. The Winchester has a better designed stock that almost never cracks in the web between the trigger and the magazine box.

 

[TRX]

So, sifting through the PR-speak, they only have line contact between the bolt and receiver instead of a true bearing surface.

That could be one reason they're claiming 53Rc hardness for the bolt and receiver... the load on the line is going to be quite high.

With line contact, the bolt face is going to move back slightly in relation to the breechface every time the rifle is fired, as the line contact smears out and springs back. To the case head it would look like a rear-locking action.

Gunsmiths lap bearing areas because the factories manage to meet their standards of accuracy with fairly loose tolerances. If you want both lugs and the receiver to all meet up nicely it's just a matter of using a little more care with conventional designs and machinery. Factories don't always put that amount of care in because, from their point of view, it's a waste of time and money.

It's an interesting design, but... "That word. I do not think it means what you think it means."

 

[bush3755]

CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The High Road, nor the staff of THR assume any liability for any damage or injury resulting from use of this information.

Regarding extraction issues with bolts having different lug counts, proof loads with 30 to 40 percent more peak pressure than standard loads. The empty, once fired cases will typically drop free from a chamber by the force of gravity. I've shot a few in my day and no extra force is needed to extract them. And they'll drop fully back into the chamber from the force of gravity. Military teams shot proof load equivalents in M1 and M14 match rifles with converted M80 ball ammo; 148-gr. bullet was replaced with a 168- or 172-gr. match bullet that raised peak pressure from 50K cup to 70K cup. No extraction issues with that stuff shot in bolt guns, also.

If proper full length sized cases are used for reloads, there won't be any force needed to pull them back out of the chamber. Neck only sized cases may end up binding the bolt upon its opening, but that's most often caused by out of square bolt faces and the out of square case heads they cause.

I doubt a Remington bolt will seal high pressure gases with its shroud around the case head expanding against the barrel. Before gas pressure from leaking gas gets high enough to do that, it'll be squirting back into the action through the two holes in the bolt face; one small and one large. Which means gas will also be squirting out between the bolt head and barrel recess for it. If the gas pressure is still high enough to seal the bolt head to the barrel in spite of the two holes in the bolt face letting gas out, the barrel will probably burst.

Lock time with M98 Mauser actions is about the longest of all at about 8 milliseconds. M1903's and M1917's are medium; 5 to 6 milliseconds. Win 70's are about 3 milliseconds and Rem 700's about 2.5. Titanium firing pins shorten lock times about 30%. M1 and M14 lock times are about that of a revolver; a long time.

 

[GAMEOVER44]

I believe bolt-action rifles are the most DEPENDABLE firearm types by far on the market. You get a sure feed each and every time.

 

[taliv]

not in my experience. at matches, i see way more people screw up loading and cycling a bolt gun than an ar15.

 

[bush3755]

I've gleaned from high power match rifle competitors that the Winchester 70 actions are the most reliable in feeding of all conventional rifle designs. Especially in rapid fire matches where 10 shots are fired with the second five charged into the magazine via stripper clip; all in 60 seconds. As were the M1903 and the Win. 54. All easily field stripped and all that's needed to replace any key action part was a pocket knife and a pair of pliers.

Remmies oft times fell short; magazine design and too short and poorly shaped bolt handle. And their extractors broke a lot; I replaced two of them on my one and only M700. Triggers wouldn't hold pull settings and some were not safe.

Today's most reliable are tube guns such as the T2K or Eliseo match rifles. They're also the easiest to build and shoot for best accuracy.

But I think the double rifle still remains the most reliable in spite of its 2-round capacity. Good users will carry 2 extra rounds with their rims tucked between two fingers in the off hand they'll put under the fore end. After two shots are fired, the rifle can be broke open, the second two rounds chambered then the rifle closed and the second 2 shots fired. All in 8 seconds starting in a off shoulder, muzzle down, carry position using a sling.

 

[GAMEOVER44]

Thats probably because there rushing the action not allowing the empty cartridge to fully eject. AR15s are NOTORIOUS for FTFs..

 

[bush3755]

I don't think slow operation of Rem. actions were/are the cause of their failure to feed issues. Rem's eject empties as soon as the case mouths clear the breech end of the barrel and the spring loaded ejector flips them clear. Their FTF's were magazine and follower problems but they may be better these days.

Win. classic actions need about 5/8 inch more rearward bolt travel before the ejector slides into the bolt head and pushes the case out. However, if they're short stroked and the empty is still held in the bolt face by the extractor, the empty will sometimes stay in the bolt face and jam the action with the top round in the box magazine.

Big 5 African game hunters have told me their guides preferred clients use Winchester or magnum Mausers (Brevex?) over Remington for large bore bolt guns. And the Rem's were notorious for bending their recoil lugs.

 

[Howard Roark]

Winchester 70 actions are the most reliable in feeding. Especially in rapid fire matches

The T2K and Eliseo bolt guns which are magazine fed are far superior to anything with a stripper clip for rapid fire. If I had to shoot a Win 70 or Rem 700 I'd go back to an AR-15 in a boutique caliber.

 

[243winxb]

See post #10