Mauser action thread question

[Joe Portale]

Okay this might be anther one of those questions that may make you think I have too much time on my hands...

I was looking at a Turk Mauser action, 98 threaded to small ring. The ID is .98 and true large ring has an ID of 1.1, this is a difference of .12". Would it be feasible to chase the small ring threads with a large ring tap? Or would I risk cracking the receiver?

 

[saands]

Well ... Not having done what you have proposed, the following is JUST an opinion. IIRC the threads are 13 pitch ... that means that they are about .050" deep (I based this on 60 degree threads while your Turk asctually has 55 degree threads, but I was unsure from where the 55 deg is measured) ... close enough. Even if you started out with a tube with an ID of the root diameter of the Turk threads you would STILL have too much metal to use a tap ... I'd say that the receiver will survive but you'd likely go through more taps than it would cost to buy a new rifle. Have you thought of turning down the barrel in question ... that's what I'm doing with my Turk project.

Good Luck,
Saands

 

[Joe Portale]

Saands,

Thaks for the input. This is one of those I'm up at 4:30 in the morning and my mind is wandering questions. You are right the Mausers us a Witworth thread, with a 55 degree pressure angle. This is the measure of the thread slope from the root to the crown. I have a set of taps and dies that I use to chase the Witworth threads into ASE 60 degree angles. This way it makes the barrel threading easier. I have heard that some gun plumbers will take a SAE threaded barrel and just screw it in to a Mauser receiver without mating the threads. They will go together okay, they just wouldn't stay tight.

I may try to see if the 1.1" bottoming tap I have will line up on a cracked Turk receiver that I'm using as a paper weight. In an idle moment I did the math using standard drill-tap charts and the .98 is real close to a 80% tap hole. This may actually be too big for a clean thread cut. I'll let you know what happens.

Promised Honey-Bunny Jambalya for supper tonight, gotta go.