installing new barrel on a mauser receiver

[Dixie Gunsmithing]

Jim,

Babbitt is an alloy (white metal) with a low melting point similar to or lower than solder. It has several different formulas, according to who made it, but the trick of it is, casting it around the barrel to get an exact taper to grip it with. I think Brownell's sells it too, or they used to, in bars. You can easily melt it in a lead pot, then pour it into a mold. It was designed to be poured into molds with pillow blocks to form bearings for line shafting. It's really good for split bushings in barrel vises.

On the wooden blocks, you just need them big enough, and with enough surface area to not slip, and adding rosin helps this. I drill them to a size for the smallest diameter of the barrel I want to grip, then taper them with a sanding drum, or a, adjustable taper reamer, which leaves a coarse cut behind. Once done, I split them in two with a band saw.

 

[HankC1]

Quote:
Barrel shank length = (Distance from Inner Collar to Receiver face) - .002" (for crush depth).

The same way I calculate it too.

If the shank length is shorter than collar-to-face distance, the shoulder would contact the receiver face first and shoulder would be the main contact point instead of inner collar. Should it be +0.002" instead of -0.002" if sitting on Inner Collar is more desirable.

For Mauser's 12 TPI thread, barrel turns 360 degrees per 1/12" advance, or 360x12 degrees per inch advance of thread.

0.002" = 0.002X360x12=8.64 degrees turn from hand tight (barrel touches inner collar). Does not take much torque to apply 8.64 degrees, I guess maybe no more than 40 ft-lbs. So, the shoulder will be pressed hard against receiver face as well when a typical 80 ft-lb is applied to install a barrel.

 

[4V50 Gary]

We apply dykem on two places of the shank. First would be on the breech end of the barrel shank that contacts the C ring/collar. The second is at the shoulder where barrel will contact the breech face. When we slam our barrels on and then pull them off, we check those spots. If the dykem is removed, that ensures us of contact at both points. The barrel is then reinstalled and slammed on again (you can tell by the action wrench if it's at the same point).