Gunsmith

[Gus Youmans]

I have a VZ24 Mauser action that I suspect may be soft. I would appreciate information on gunsmith(s) who can check the action to see if it is soft and, if possible, reheat treat it.

Thanks,

Gus Youmans

[waksupi]

May I ask, what makes you think it may be soft?

[Gus Youmans]

waksupi,

First, the gun has been completely sporterized including a Model 70-style safety and wears a Douglas barrel in 8X57 Mauser. I was experiencing difficulty opening the action even with reloads using Lyman's starting loads. I took the gun to an old guy who used to build a lot of sporters on old military actions and he set the barrel back and rechambered it. He did not have the ability to test the action for softness and I do not want to shoot the gun until it has been tested. Prior to noticing the hard bolt lift I shot several hundred rounds of old Romanian surplus ammo through the gun but don't remember any immediate indications that the ammo was too hot.

I have considered using the gun with only cast bullets but am concerned that the gun may be unsafe with standard ammunition and that some future owner may get hurt because of it.

My plan is to take the barrel off and have it installed on another action before the sending the questionable action off to have it checked - if I can find someone who can do it.

Gus Youmans

[MaLar]

I built a 35 Whelen on one and ran some top loads through it, never exceeding book loads.
Unless it's been trough a fire it'll be a good action.

[M-Tecs]

These actions are case hardened. If the receiver lugs have been trued they may have gone too deep and went through the case hardening. There are a various other reason for the hard bolt lift. Not sure what the old guy checked but redo the process of elimination doing the easiest checks first? Is it difficulty opening only when fired or always when you cycle the action? Extractor fit, trigger, cocking piece, scope mount screws etc. can all cause issues.

What state are you in?

Not sure if they are still doing them but Blanchards in Utah used to do case hardening on Mausers. https://www.bmproc.com/heat-treating

[405grain]

Generally the VZ-24 actions are very good. Czechoslovakia was not denied strategic materials like Germany was following the treaty of Versailles. This means that while German 98 Mauser's were still case hardened low carbon steel, the VZ-24 could benefit from alloy steels. That being said, no rifle ever made can stand abuse for long. If your rifle was used for firing over-pressure rounds it may have developed bolt lug setback. This is where the lugs on the bolt push back and dent into the lug recesses in the receiver. If this has happened it will cause the effects that you are seeing.

If the receiver has bolt lug setback the dents in the receiver will cause excessive headspace. When the rifle is fired the cartridge case will stretch and force the bolt lugs back into these dents. The stretched case will hold the bolt back, and to open the bolt you will have to apply enough force to compress the case and "lift" the bolt lugs out of the dents. These dents may only be .005" deep. or they could be up to .020" deep in extreme cases (like on a very soft small ring action with way too much pressure). However much the bolt has set back, that's how much excessive headspace you'll have.

Not only will this make the bolt hard to open, the stretched cases may get dangerously close to an incipient case head separation. If the case breaks just forward of the case head the results could be catastrophic. Look to see if there's a shiny ring on your spent cases about 3/8" ahead of the case head. Also, make a "feeler tool" out of a paper clip and check the inside of the case for a ring where the case might have thinned. If your getting this then there's a pretty good chance that you may have bolt lug setback. With the firearm empty pull back a little on the bolt handle and lift the bolt. Do you feel the bolt camming forward slightly? If you can feel that you have a lot of setback. If the setback is moderate if might be hard to feel this way.

If you have bolt lug setback here's some bad news. First, all the hardening in the world isn't going to correct that problem. It is dangerous to use an action that has setback. It usually, in fact almost always, costs so much to fix a receiver with this that the action is scrap. To check for bolt lug setback you will need to pull the barrel and look at the bolt lug recesses inside the receiver ring. If they have been dented even a little bit do not use that action any more.

There may be another reason that setback can occur besides pressure overloads from too hot ammo. Mauser actions are case hardened. That means there's a hardened high carbon steel case around a softer steel core. This case is only a few thousandths of an inch thick. (around .025" is typical, though the case may be thinner or thicker depending on the manufacturer) One of the common home gunsmithing processes with Mauser actions is to lap the bolt lugs to match the action. If a previous owner had done this and been overzealous, they might have ground away most or all of the case hardening on the lug recesses.

If you discover that your receiver has setback, there is a way to fix it. You, or your gunsmith, will need to make a tool that inserts a hardened steel disc on a spindle into the receiver ring. the disc is rotated with valve lapping compound to grind down the face of the lug abutments. These cannot be machined flat with a boring bar because the interrupted cut will cause way too much chatter. To get a flat surface the abutments need to be ground. This process will remove the case hardening, so after the setback is removed the receiver will need to be case hardened again. The barrel will have to be set back too so that it will compensate for the bolt face now being farther back from the breech. I did this process on a 93 Mauser that I converted to 223, and it works. It is very likely that doing this will cost much more than the rifle is worth.

As a first step I would recommend that you have a gunsmith pull the barrel and inspect if your action has setback. If it does, then you need to make a decision of getting a new receiver or repairing the one you have. I cannot tell if your action has setback or not, but what you describe sounds like the symptoms of it, so check and be sure.

[405grain]

I just read M-Tecs post and it reminded me that I was once gifted a M38 Turkish action because the bolt was hard to open. It turned out that the rear action screw was too long. The lesson here is that it could be a number of things, so like M-Tecs said eliminate the simple stuff first.

[waksupi]

I just read M-Tecs post and it reminded me that I was once gifted a M38 Turkish action because the bolt was hard to open. It turned out that the rear action screw was too long. The lesson here is that it could be a number of things, so like M-Tecs said eliminate the simple stuff first.

That's kind of what I'm thinking. Something over looked. I had one I found the scope base screws were too long, and dragging the bolt.