Home Forums Hunting & Shooting Gunsmithing Question on installing short-chambered prethreaded Mauser barrel

Building a truck gun on a VZ24 action in 22-250. I've wanted to do one myself for years now, so this is it. Received the barrel yesterday, and it gets tight after about 1 turn as I thread it into receiver. Is this normal?

I do have the barrel vise and action wrench to torque things down prior to finish reaming the chamber by hand, but not sure if the barrel should screw in by hand or not...is it routine to chase the receiver threads with a tap before rebarreling?

First time doing this, so I appreciate your input.

Brian

Chase the threads, fit should not be loose and spin like a wingnut when you get to twisting on it.

The barrel should turn in freely by hand and stop abruptly when it hits the receiver's inside collar. If there is a barrel shoulder, it should be clear of the front end of the receiver ring by a few thou. at least when the barrel is torqued to final value. This insures that the barrel is seated against the collar. If you have a receiver tap, it won't hurt to chase the threads. Check the barrel threads and clean them with a 3-square needle file to remove any burrs. If you can't screw the barrel in by hand, then the barrel threads will have to be reduced a bit on a lathe. 100 Ft-lbs is plenty of torque for the final installation.

RAN

check where you got the barrel from and ask before altering it...usually not returnable once you file the threads, etc.

I have removed and re-installed many 98 barrels that were put on 50-60 years ago, and possibly longer ago.

Most, when loosened, you could turn the remainder of the way by hand. They would go back on the same way.

A few of them, I had to unscrew the barrel all the way using the vice and action wrench, and they, or the new barrel went back on the same way--very tight.

You have a vice and action wrench. I would try to install the barrel using moderate pressure with the wrench. If it got progressivly more difficult to screw the barrel in as you progressed, then you might have to chase the threads.

Mausers threads are 55 degrees. Some replacement barrels have been known to be threaded 60 degrees, for ease of manufacture.

The 60 degree threads will screw into a 55 degree receiver, but turning it in will require some moderate force.

I know it is difficult to describe moderate force, but if the barrel will screw in without having to use two hands on the wrench or having to use a cheater bar, and it takes the same amount of force the length of the threads, it should be okay for the barrel to be a bit tight.

After screwing it in as far as it will go by hand, if you have to really bear down and strain to turn it further with the action wrench, then the threads are messed up, somewhere. It could be possible that the barrel threads are not quite deep enough, or the shank was not turned down far enough.

Do you still have the original barrel? If so, test to see how easy it is to screw back in.

Thanks for all the advise; I appreciate the help! I used a bronze brush to clean the threads on both action and barrel, and was able to get about two turns before it got tight. Also looks like the action threads got dinged when it was D&T'd, so I called 4-D and rented their LR98 action tap. I'll chase the threads out and see how it goes from there. Double checked Kuhnhausen's book, and he recommends chasing the threads due to the thread angle mismatch with prethreaded barrels. Guess I should have reread that before posting Once I've chased them, I'll see how it turns in using the vise and wrench - good description on the moderate force, and I'll definitely check for increasing tightness so I don't induce any stress in the barrel.

If all else fails, my local smith is more than willing to help me out in turning down the barrel threads. He's aware of what I'm doing and will help out if needed, I just want to get it done myself if possible.

I bought this as a bare action, so I can't check the original barrel. Threads look good except for where the front scope base screw goes through them, so hopefully the tap will fix it.

Thanks again!

Brian

Here's a question fom a non-gunsmith to those that know.

First off, I unsterstand that if the pitch of the threads is off then recutting the threads is the way to go.

But - what about using a little lapping compound to chase the threads? The only reason I'm asking is, I've done this on many threaded parts to clean the threads up a bit with very good results.

I'm just curious and not suggesting anything.

It is mentioned in a few books I have, but very cautiously. Also is mentioned lapping the barrel to the receiver face or recoil lug, but without getting compound into the threads. So go figure.