Anybody Up To Speed on Mauser Feeding Geometry?

[Bigslug]

In this case, it's a pre-64 Model 70 .30-06 but same family.

No issues at all running ball '06 or other spitzers, but the Accurate 31-194D round (ish) nose is giving me some problems.

The load feeds fine off the right side of the mag, but from the left, the bullet crosses over to the right and the meplat jams up in the extractor cutout at the back of the chamber.

My Ruger 77MKII / Hawkeye eats the same load like popcorn. I have access to a few other Mauser-family '06's I can try it in, but this one's frustrating, as that bullet was supposed to be my "One to Rule Them All", and not being able to use it for speed runs through one of the slickest actions out there is quite the bummer.

Any thoughts?

[waksupi]

Are you working the bolt as intended on a Mauser? Treating it like a rented mule?

I've had a couple rifles I relieved the extractor cut a bit to allow easier feeding, but you pretty much have to remove the barrel to do it properly.

[xtriggerman]

These are hard to diagnose without haveing the problem in my hands as you can guess so this is a basic stab at it. First off, the pre 64 is a fine action but the finish work on the feed ramp could be improved. If the lead tip is stalling on the machine lines, that could greatly affect the direction of the cartridge. FMJ's would have little to no drag on a factory rough machined ramp. Cartridge tension is up next along with magazine well conformity. Make sure your magazine well walls are not wider than they should be by taking the follower and spring out of the floor plate and run your finger over the mag well wall where it mates to the receiver cartridge cut. It should make a seamless fit at that joint with the mag well wall matching the receiver edge perfectly. Then be sure the mag spring has not been messed with by being stretched. normally, the spring should be weaker at the front than at the rear. At times this spring tension may need to be modified in accordance with what symptom the feed is dealing with. It sounds like the rim is being retained for too much of its mag containment stroke so the opposite mag wall may be at fault with opposing cartridge tension. Lastly, The receiver feed lip may in worst case need to be relieved slightly to allow the cartridge release slightly earlier in its movement out of the mag if all else fails to remedy the situation. You cant go wrong with a good feed ramp polishing right off the bat with pressured cut & polish focus on the left side. Good luck with it.

[Mk42gunner]

I have absolutely no idea if it is still on the internet or not, but more than twenty years ago there was an article by Darcy Echols IIRC on Mauser magazine geometry. Very informative on how cartridges stack in the magazine, both base and shoulder diameter and length can make a big difference.

I remember reading it before I retired in March 2004.

Robert

[WILCO]

I have absolutely no idea if it is still on the internet or not, but more than twenty years ago there was an article by Darcy Echols IIRC on Mauser magazine geometry. Very informative on how cartridges stack in the magazine, both base and shoulder diameter and length can make a big difference.

I remember reading it before I retired in March 2004.

Robert

https://gunsmagazine.com/discover/the-mauser-magic/

[Mk42gunner]

Thanks Wilco for finding that, unfortunately it is not the article I was thinking of. The one I remember explained how the cartridges were supposed to stack in a perfect triangle in the magazine box.

Wish I could remember were I saw it. That was several computers ago and this one is on its last legs.

Robert

[Delkal]

If you are only having problems with that one bullet it is not a rifle or geometry problem. Seat the bullet shorter and see what happens. Or consider a more traditionally tapered bullet or a round nose.

[K43]

Ditto what Delkal said.
Don't go changing feed ramps on the receiver before trying different seating depths or changing to a different bullet. Stoning or filing on a receiver is permanent and can really mess things up.
I've gotten 308 and 270 to feed in 98 actions and 300 Savage to feed in a small ring Mauser by just changing the follower.
Changing the seating depth or just flat out using a different bullet is cheaper and doesn't hurt the rifle permanently.

[Bigslug]

If you are only having problems with that one bullet it is not a rifle or geometry problem. Seat the bullet shorter and see what happens. Or consider a more traditionally tapered bullet or a round nose.

Seated it shorter to the point the front driving band was almost gone - didn't help. Comparative analysis of other controlled feed .30-06's tomorrow.

[Delkal]

Seated it shorter to the point the front driving band was almost gone - didn't help. Comparative analysis of other controlled feed .30-06's tomorrow.

Longer? (assuming it will fit)

[xtriggerman]

Yeah, maybe these guys are entirely correct that bullet depth is at the core issue here. 43 years of professionally trained gunsmithing experience tells me probably not but hey its non invasive so yeah, try anything like that first. Must be the pre 64's that came over my bench were one of's with feed ramps so poorly finished you could about cut your finger nails on their machined surfaces. But dont fault Winchester, they were bleeding money big time back then. I made the mistake of not saying if your not skilled in gunsmithing techniques, don't apply anything that removes metal to your gun. On the other hand, my post may lead one to understand what "may" be involved in getting the gun to feed left side into the bore than way over into the extractor cut. I'll be more careful with my opinion next time since like I said, sight unseen would be nothing definitive right off the bat. The best advice is always find a qualified gunsmith if fiddling around with OAL of a round doesn't help. Seems thats what the others are saying and they are indeed correct.

[Bigslug]

Had the opportunity to take a hard look at this gun, the Ruger, a CZ 550, and a Brazilian 08/34 (essentially a K98) and run the same load through them. Only the Ruger eats them flawlessly, but the reason seems to be appearing.

The point on the bullet at which the ogive nears full diameter seems to be what bears on the feed ramp at roughly 5:00 and 7:00 to guide the bullet to the chamber. With a lengthy bore riding nose section, that contact with the ramp starts a lot sooner than with a jacketed spitzer, and that has the potential to kick the nose of the bullet too far right or left to enter the chamber successfully. Another part of the problem is that this long nose screws up the rifle's timing - the nose is getting fed before the extractor has a chance to grab hold. The Ruger's ramp seems to be shallower and wider and is thus more forgiving of bullet shape.

Need to take a harder look and take some measurements to see if what's possible. The final decision may well be to do nothing, but it's at least an education.

[405grain]

I just read through this thread today. There is very likely nothing wrong with your model 70. With a more standard configuration cartridge you could probably cycle the action with your little finger. The barrel has a coned breech, which makes it even more likely to feed properly than a Mauser (which is no slouch). I'm not a professional gunsmith, but i do work on feed rails and feed ramps, and understand what to do on them to "aim" the cartridge into the chamber, and release the cartridge so that it comes up under the extractor claw. I would advise that you don't alter the M70, and instead select a different cast bullet.

[Texas by God]

Just for grins, hold the barreled action upside down and look at the action sidewalls under the rails- especially the ejector side- for burrs.
Getting the cartridge to sit just a bit more to left might help.
It’s worth a look.
This is Mauser experience talking, not Pre64 m70 experience so it’s worth what you paid for it….


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[Rich/WIS]

The RN like the 311291 feed fine in my 03A3 and in a pre-64 M70 I used to own. The 311041 with the flat point would hang up in the extractor cut on both. The drawing for the 31-194 looks similar to the 311041 and being linger is likely hitting the extractor cut before pivoting into the chamber. When using the 311041 it it jammed pulling the bolt back an inch or so and going forward would usually let it feed. You may want to consider a different bullet mold. FWIW the 311284 fed fine in both rifles.

[Bigslug]

Wisdom came in the form of an old box of Remington 220 grain round nose Core Lokt I found kicking around. Those ran fine in the mentioned sample guns. I then tried matching the longer OAL of those rounds with the 31-194D, but more problems presented.

It turns out to be a matter of nose taper.

The long bore ride section and blunt nose of the 31-194D is causing the cartridge to nose-up sooner and more abruptly, forcing the rim end of the cartridge down and out of engagement with the extractor, creating a situation of bolt override. The Core Lokts have a more pronounced taper causing the cartridges to rise at a much shallower angle. The Ruger Hawkeye appears to have a shallower ramp that allows the 194D to feed in about the same way, but it's a no-go for the older pattern CRF guns. It looks like the answer will either be my NOE 311299 clone, or if I want something with a meplat, the Accurate 31-200M, or 200V (which appear to match the Core Lokt profile pretty closely), or possibly the 200L - which is Tom's version of the 311299 with the point lopped off.

Magazine geometry. . . does not always mesh perfectly with chamber geometry.