Mauser Barrel Fitting
By Clemson

Why I fit to the Primary Torque Shoulder

There was a discussion on this issue a while back, and there is some disagreement as to how to fit a Mauser barrel. Here is my take on the issue, no charge....

The Mauser Model 98 action has an inner shoulder called the "Primary Torque Shoulder." It is also called the "C Ring" and the "Inner Torque Shoulder." This is the surface that Mauser intended for barrels to be set against, but why? We know that Remington and most other modern manufacturers seat the barrel against the front of the receiver ring ("Secondary Torque Shoulder"). They don't even have an inner ring.

The answer is in the geometry. I took measurements on a barrel that I had sitting on the bench. It is an Adams & Bennet F34 .30-06 barrel, and I figure that it is typical of sporter dimensions. I also measured a Czech 98/22 receiver. Here are the numbers:

The actual contact area is 60% greater on the Primary Torque Shoulder. I actually cut the tenon about 0.002 inches long. That way when I draw up the action to the barrel, the Primary surfaces bottom hard (i.e., "crush fit"), and the barrel shoulder actually draws up to the feceiver face. That is not, however, necessary. It is really more cosmetic than functional.

Now the above is all about sporter barrels. Military barrels are another kettle of fish. I measured a take-off barrel from a Yugo M48 Mauser. The shank diameter is 1.113 inches and the thread diameter is 1.102 inches. Those numbers would yield a contact area on the front (our A1) of 0.0191 square inches. That would make A2 14.4 times larger than A1. Obviously, seating on the front of the receiver is not even an option for a military barrel. Small ring Mauser barrels have threads that are 0.980 inches in diamter. Throw those numbers into the calculations, and the surface available on the front ring is 0.2186 square inches -- a lot more reasonable surface to deal with. The small ring barrels ARE seated against the front ring.

For what it's worth..........
Clemson

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''Clemson'' for this HowTo !

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