Home Forums Hunting & Shooting Gunsmithing Mauser bolt face primer erosion

Dang, my near pristine Venezuelan mauser now has a pock mark on the bolt face. Loaded some 150 grain Sierra MKs and went to see how they would group. Twenty four had no issues, but one primer (WLR) blew out right on the cup curve and eroded a small mark on the bolt face (loaded below max). I know it is only cosmetic, but Arrrgggg, it ticks me off. If I was to get a new FN bolt from Sarco, how would a gunsmith go about headspacing it or is it a buy and try proposition to get one properly headspaced? Grouped great by the way, 1.5" at 100 and 3.5" at 200 open sights. I think I can do better with a better target that I can see.

The barrel would be set back, one turn probably, and then a finish reamer until headspace was correct. Stock inletting may have to be "adjusted" slightly. And if your bolt is matched you wouldn't have a matching bolt #.

One small mark on the bolt face? Must be the cleanest Mauser bolt face in the world.

I say don't frell with it.

Take it to someone that knows what they are doing, have it micro tig welded. No need to set the barrel back then

It was essentially unused until I got it last year and I have fired less than 100 rounds through it. The only blemishes were a few small dings in the wood. I would like to simply have another bolt properly fitted and I know Sarco has a bunch of new FN mauser bolts that are un-numbered, but getting one that would properly headspace with no additional work may be like looking for a needle in a haystack. I would keep the numbered one and use the replacement when I wanted to shoot, just in case I ever decide to sell it.

You can have it welded up, but it will need to be re-heat treated & tempered afterward. I know a guy in Arkansas who does such work. He's a busy man, generally works on Purdey's, Hollands, and such. But if you like, I can reach out to him to see if he has time in his calendar. He has a Tig welder, and a heat treating furnace and knows how to use both well. Just PM me if you want me to contact him.

Don't look at it and it won't bother you

That's kinda putting the cart before the horse. The thing to do if one was intetnt on swapping bolts would be to check headspace with the new bolt in place. There are three possibilities: Headspace will be too little, it will be too great, or it will be just right.

If it is too little by not too much, you can set the headspace by truing the boltface. If it is short by too much then a reamer will be used.

If it is too long the cure depends on whether the barrel has sights or not. No sights, just trim the shoulders until headspace is correct. Sights, set barrel back a turn and ream.

Just right, count your blessings.

Me, for one small pock mark, I'd just continue to shoot it.

Good post...and remember, there is wiggle room in headspace. Everyone seems to forget that third headspace gauge; Field. If you can get it to not close on a Field gauge, and she still shoots true; the job is done. Everyone wants "minimum" headspace, very few have a clue as to what that actually means (most times, nothing at all).

Yes, there's more than one way to skin a cat.

Yes, but why someone would opt for the most extreme fix when it may not even be needed is beyond me.

Why amputate a leg, when antibiotics may be all that are needed?

As you said, "Stock inletting may have to be "adjusted" slightly."

Why introduce a stock gap when it may not be required?

Just saying.

Start with the least invasive procedure first. In the end, yes, perhaps setting the barrel back is needed.

Unless it represented a clear and present danger I wouldn't sweat it. Heck, half of my rifles have some kind of imperfection on their bolt faces and/or standing breeches- and yes I take pride in ownership and admire them for their condition/cleanliness. For me there are a bazillion other more important things to worry about than a tiny pit on a bolt face.

I have to agree.

Yes, I know, but it is just the fact that it is now 'flawed'. Kind of like buying a new car and while your driving it home, you get a dang rock chip in the window - it doesn't hurt anything per say, but it just pisses you off or finding out that the neighborhood kid down the street soiled your teenage daughter - not much you can do about it, but not happy about it either. At least I CAN get my mauser bolt face repaired to almost like new, unless I can fit a new, unnumbered one.

I was not at all disagreeing.

May not be a headspace problem, at all. If your brass isn't trimmed to the correct length, it can create high pressures and blow primers. I have replaced the blown out extractor in a customer's rifle twice for this very reason. I have warned him repeatedly not to use his "Buddy's" reloads. Now he gets it.

Why bother, it is likely that another will appear and annoy you again.

When that sort of thing happens to me, I heave a big sigh of relief for then I don't have to worry about getting that "first ding", and get on with using the vehicle as it was intended. One time my then GF dropped a small tree across the bed of my brand spanking new Toyota 4X4 (she fancied herself a chainsaw artist). I hugged her and laughed it off, and drove that thing for 200,000 miles with those glaring dents on the gunwales of the bed. Didn't effect the trucks performance one iota. Sure, I try to take good care of my guns, cars, and sweethearts- but I'm not anal enough about it to fret a tiny blemish on any of them.

I have been sporterizing Mausers for 49 years.
The Kuehnhausen books on Colt double action revolvers are so good and the his book on Mausers is so bad, I can only speculate what happened.

This is speculation..

The Colt factory spoon fed him with in house manuals that were very good. Then they proof read his books for him.

The Mauser book was just some lecture notes from teaching a class, without the drawings that would have been on the black board. No editor alive would have allowed that mess to be published because of the scatter brain organization. It went to publication without being read. The verbal part of the lectures about money were left out. Like, "We all know that the interior structure of a Mauser is soft, but if you really want to screw over a client and take him for all he is worth, tell him you are sending out his Mauser for heat treat. [class laughing]"

Then something happened. It was like the Roswell incident. The gov said the balloon was a flying saucer, and that information fell on fertile ground. Many WANTED to believe that.

Likewise Kuehnhausen has spawned a generation of Mauser heat treat believers that true Mauser bolt faces while wearing tin foil hats.

If you find a good gunsmith, he should be able to Tig the pit carefully, put it in the lathe and clean up the weld and the bolt face so you can't tell it was ever damaged. If it is done properly, a good Tig welder won't affect the temper for such a small repair and it will be like new.

Bob