I have read conflicting information on the fit of the barrel shoulder on a mauser action. Does the barrel have to fit at both shoulders, barrel base and action or just one?

The answer is NO, it does not have to contact both shoulders. The Mauser action was designed to contact only on the primary torque face inside the action.

But many custom Mausers have the barrels cut so that 80% of the torque is on the pimary face and the shoulder of the barrel cut contacts the front face of the action (secondary torque face) just before the final torque value is reached. I don't know if anybody has ever "proved" that this helps performance, but it looks better.

Every 'smith I know (about 1/50,000th of the total population of 'smiths)insists the barrel shoulder should not bear on the receiver ring. LaBounty cuts a draft on the shoulder so he can creep up on the appearance of contact without torquing the front of the ring. All of the hunting guns I have had barreled in this manner have shot side by side with the best of any other hunting action.

I always figured I would get a stiffer connection if I had contact with both, stretching the rear threads and compressing the front threads.

But in de barrelling alot of military Mausers, I notice gualing on the "C" ring [inner torque shoulder], but none on the large ring. This would support the theory that the inner shoulder bears the compression.

I have noticed that the Mosin Nagant design had two shoulders from 1891 to 1941, but from 1941 on, the inner shoulder is missing.


But in the end it doesn't matter much, I have varied the torque from 2 foot pounds to 2000 foot pounds, and the accuracy does not change much.

Whether it bears on the inner ring, or the shoulder, the main thing to keep in mind is that it should only bear on one. The main reason for this is the simple fact that two surfaces that reside in the same vertical plane cannot both locate the barrel square to the threads. While perceived deviation in most cases might not be much, one of the surfaces has to be the primary locator.
After some considerable research on the subject, and many a gutted mausers to look at, I'd have to say that Paul's intent was for the shoulder to float, allowing all and primary contact to reside on the inner ring, which in the world of mechanics makes the most sense.
We normally leave a .001-.002" clearance between the shoulder and the front ring. Now I know there are some keen eyes out there, but for the average 20-20 vision, that's pretty damn close. Enough to be overlooked, and dismissed as touching by probably 99% of the people doing the looking.

Kuhnhausen is often considered the standard Mauser reference. He states that (for M98) the secondary torque face (barrel shoulder to receiver front ring) should be clearanced by .001 to .0015 when hand tight.

This places the max torque on the primary (internal) face, but the secondary shoulder will contact when wrenched tight.

As I said before, I think anywhere from 80 to 100% of the forces should be on the primary face. I think it matters greatly on the M98 which face should bear. If only one is to bear it MUST be the primary (inside) face.

I'm kind of semi-tall but,even so, I occasionally have a statement fly right over my head.
Matt, If both surfaces are in the same vertical plane, I take that to mean they are parallel. If this is the case, it follows that if one surface is perpendicular to the axis of the threads then so is the other. Therefor, I would think that either or both contact points would locate the barrel in relation to the threads. Naturally if either surface is not perpendicular to the axis of the threads, all bets are off!
I have always set mausers up and cut the face of the receiver so that it is parallel to the inner shoulder then fit the barrel to contact the front first then the collar. Apparently this is wrong and I should probably be flogged. Especially since I knew full well that Mauser fitted the barrel against the collar only. And had read Kunhausen's book. This kind of flagrant disregard of the manufacturer's intent and the instructions of a host of experts points out what must be a serious character flaw. Sadly, there are already two generations following me which may posess the same trait.
I fit other actions with inner sufaces the same way. The Weatherby MkV for instance or the 788 Remington. With the 788, I allow about .002 crush on the recoil lug to be sure it is held securely. The Voere, which features an insert into which the locking lugs seat, is treated the same way.
In my mind, poor thing that it is, the "double seat" is more rigid. While I can't necessarily prove that my methods of doing things are superior, I've not seen it demonstrated that they are inferior either. So there! Regards, Bill.

And Bill, in my mind the larger diameter of the receiver ring/barrel shoulder offers more rigidity than would the smaller diameter of the thread tennon bearing on the inner collar, making for more accuracy potential. So, like you, I find it more appealing to fit the receiver ring first, inner collar second.

Pat Byrne

I true the face and inner ring. Then cut the shank length to allow the shoulder and inner ring to crush and equally. I must be doing it wrong as well.

See there Darcy, you didn't listen to your instructor in gunsmith school, or me and George, shame on you!! I'd a thought after building a million rifles you'd get it right sooner or later..

I assure you D'Arcy does it the right way.....He is a fair to midland smithie..

Ray
What with all this conflicting data I'm almost afraid to turn the key in the door each morning as I expect the contents to implode at any moment.

I have been trying to think of what Paul Mauser was thinking.

Maybe the inner ring bears the force, and the outer ring acts as a damper to reduce vibration. That might be more important than my first inclination of pursuing stiffness.

--
A society that teaches evolution as fact will breed a generation of atheists that will destroy the society. It is Darwinian.