Sometimes you win, sometimes you lose, and sometimes you get it right in the seat. This is one of the latter. Bought a cheap Herters Mauser 300 win mag off GB, figured to use as a truck/beater gun. Action was fairly rough, but blueing was nice and pretty. Then once I took it apart, discovered the stock was cracked in 3-4 places. Time passes, I found another stock, bedded it, shot the rifle, it was pretty accurate, consistently 3/4 MOA with 180 accubonds.

Then, when cleaning the rifle, discovered the bolt body was cracked, right along the underside. The crack runs all the way through the body. Pics attached.

Any ideas of how to salvage *something* out of this? I basically have a barrel and a rough action.

Snag a bolt off EBay and check headspace. If it’s short rent a reamer and ream it by hand. If it’s long sell the bolt and try again or have it set back a thread.

How the H did that happen? Not an expert by any means but I think it could be Tig welded. Almost all the stress is on the lugs so the bolt body is less critical. Ask Dan's in Alaska as he is specialists in bolt welding. But I hope someone smarter more versed in metallurgy chimes in to verify or deny this idea.

Been trying the Ebay route but it's a magnum bolt face so have not been having good luck. Had not considered welding it.

A standard boltface bolt can be easily modified to a Magnum boltface.

That crack is suspicious. It looks like the bolt was made from dom tubing instead of a pice of round stock and split where it is welded. Heat paste the lugs. Have it Tig welded and go on.

I believe that Herter's mauser (if it is what they called a Herter's J9 improved mauser) was actually made by ZC (Zastava, not to be confused with CZ in Czech...). If so a Zastava bolt as in the 70's Interarms mauser might fit. Just a thought to consider. Good luck.

I would guess a flaw in the steel from the low stress location. Send it back to Herter's for warranty service.

Don't know why somebody that knew how to control heat couldn't just TIG it. Or stop drill the crack and ignore it. And show it to people to scare them. (You wanna borrow my rifle? Sure. But let me show ya this.)

I'll def send back to Herters to get warrantied. Ha.

A gunsmith told me that for the bolt to crack in that location, it was probably too hard, which might imply the lugs were too hard as well, and could lead to some other issue with the lugs similarly cracking etc. I'll probably keep hunting a bolt.

Dan40x is the Tig guru. Daninalaska is a halibut guru, among other things...

Thanks for the clarification. I don't think a Halibut would fix it.

Alright given that I have other projects, I'm putting this in the classifieds for cheap.

If I had that rifle, I would not be overly concerned although it's not pretty. I would drill a hole right at the back of the crack (1/8" should do it). This would stop the crack which likely won't extend anyway. The crack is probably a flaw rather than the result of stress. GD

First you need to find the end of the crack and then you need to drill it. Do you have any idea how hard a mauser bolt is?

Yeah, Jim, I've got some idea. Hell, at that portion of the bolt, you could spot anneal it. I have to wonder whether that crack indicates a flaw in the material or a stress crack which occurred during heat treat. Either way, it is a bit worrisome. I don't believe the Zastava actions are case hardened low carbon steel but are an alloy. GD

On the theory that the stress riser extends slightly beyond the visible crack, drill slightly ahead of the crack and let the crack run into it. Experience tells me this is a prudent approach.

Hole size isn't critical - the stress concentrated at the tiny point that is the end of a crack gets distributed around the circumference of the hole.

Run that POS through a chop saw to take it out of service.

And this is why I'm getting really tired of this site.

That is a strange place to crack. Is it possible that one of the front lugs has excessive clearance in the closed action? (causing the bolt to bend a little bit as that lug seats during firing)

I thought also that seating on the safety lug instead of the front lugs would put stress through the bolt body but that situation would be very unusual (wrong bolt - slightly too long?)

I really think the crack occurred during heat treating or, more properly, in the quench. The worrisome thing is, if the flaw was produced during manufacture, it's hard to have a lot of confidence in the rest of the bolt. I recall that Santa Barbra (another commercial Mauser manufacturer) had troubles with stress cracking when they tried to leave their receivers a little too hard. GD

Someone else agreed with greydog's assessment on the overly hard bolt...sold the whole thing to a gunsmith for parts. Too many other rifle projects.

Depends on what it's made of, the old carbon steel formula or a modern alloy. Could be as minor as a tiny slag inclusion that acted as a stress riser during normal heat treating. (We're all guessing without a metallurgical lab assessment)

As many rifle gurus there are in the Mauser world, There has to be somebody that can modify or match up a new bolt. Keep the old bolt intact so it can be measured. That bolt might never let go, or it might let you down on the next shot.....How much do you like your eyes? I'd put this bolt in the same category as the low numbered 03 Springfields.....a gamble to shoot.