Bolt face erosion?

[Wyatt Smith]

This is the bolt on my new model 70 375. It was purchased used, and I have not fired it.
The question is, What causes it, and is safe to use? If it’s safe should I use it or,should I get new bolt and have a gunsmith headspace it?
Thanks!

 

[K981985]

I’ve seen similar scars on bolt faces cause by a primer that ruptured and the hot gas etched the bolt face. I’m sure someone with more experience will set you straight, but I’d personally have a competent gunsmith check it out. I also check every used rifle I purchase with head space gauges, they are not that expensive and it only takes 5 min. You never can be 100% sure how the rifle was used or misused, or what handloads with questionable pressures were used.

 

[Wyatt Smith]

Did it happen while you were firing it? If so was it just one round? It will see a smith eventually for some customization, but I was hoping to shoot it first and see how I liked it.

 

[K981985]

One case in particular was a friends Mauser 98 sporter the scars on the bolt face were longer and not round as in your case. It happened before he purchased the rifle so we had noway of knowing the cause. One potential problem is if the cause was a really hot handload that had a primer failure the same load could have caused lug set back which will affect headspace. In my friends case the lugs were fine and the rifle shot fine the bolt face scars were cosmetic only. My point is you cannot be overly cautious. Unless you know the cause of the craters I’d err on saftey and have it checked before firing. While the model 70 has a lot of good qualities gas handling in ruptured cases is not one of them.
I may be over cautious but I once purchased a perfectly fine looking Mauser 98. The bolt had been jeweled and was polished to a fine degree. Looking at the bolt I happened to notice a tiny spot on the bolt face. Probably nothing? I got some dye penetrate testing sprays from work, cleaned dyed developer....the bolt had cracks in the bolt face and along one lug! The polishing of the bolt hid the cracks ..almost. The bolt may have held for another 1000 rounds, the bolt may also have went thru my eye on the next shot? The thing is you never know and the M70 lacks the third saftey lug of the Mauser.
Something caused the craters on your bolt something not normal and not routine. I have rifles that have fired crates of rounds with no marks on the bolt face. Like I said maybe nothing maybe something bad.

 

[IvW]

That looks real bad and could not have been caused by one failure.....

 

[Wyatt Smith]

A gunsmith told me its ok to fire. I may fire it a few times, to see how I like it. A new bolt is $300 it might be well worth it.

 

[K981985]

Did the “gunsmith” actually see the bolt or a picture? The word/phrase “gunsmith” has a wide margin for error. I’ve known “gunsmiths” that did not know what headspace was?? So any question about headspace was completely over their head. I’d ask the “gunsmith” to shoot it a few times and then access the bolt face when he was done.

 

[Wyatt Smith]

I’ve ordered a new bolt, better safe than sorry.

 

[K981985]

Wasn’t trying to ruin your day or cause you to spend more money on a rifle you just purchased. FYI a new bolt will still need to be head-spaced, the chance of a new bolt being a drop in fit is not likely. Your cheapest best option find a qualified gunsmith to look at the rifle. Maybe nothing to worry about or spend money on. But something obviously happened to the bolt. Have you contacted the seller to see if he can tell you what happened? I know most people look at the blueing and maybe the wood stock shape and call it good, the important stuff is on the inside barrel condition, bolt etc. Hope it works out for you.

 

[Wyatt Smith]

I’m going to rent a set of gauges and go from there.

 

[Dr Ray]

Looks like a leaking primer or two. That will cause erosion on the bolt face.
In other words excessive pressure!

 

[Bob Nelson 35Whelen]

I’m going to rent a set of gauges and go from there.

Wyatt Smith
Looks like a continuous use of hot loads but enlarged they look more oval. A new bolt is expensive but so are hospitals.
The cheapest and best option is to have a gunsmith mill out the offending area and replace it with an insert. A GOOD gunsmith can do this at minimal cost. Make sure it's not done by bubba the blacksmith.
Cheers mate Bob

 

[Areaonereal]

Grr Tan rifles, Greg Tannel, google it....they can repair the bolt face to like new for less than than 1/2 the cost of a new bolt...they are the best available for that type of repair.

 

[Wade J VanGinkel]

I don't have any advice but wanted to thank you for sharing this. I don't buy a lot of guns and never look at the small details ahead of time.
It's a learning experience for me.
I hope you come to the best and cheapest resolution

 

[Hogpatrol]

I'd like to see a bore scope photo of the throat on that rifle. It could be real ugly. I hope it shoots for you. That and the bolt fitting. Different strokes but if I saw that, I'd pass on the deal.

 

[Wyatt Smith]

I'd like to see a bore scope photo of the throat on that rifle. It could be real ugly. I hope it shoots for you. That and the bolt fitting. Different strokes but if I saw that, I'd pass on the deal.

I agree, I know a mechanic with a bore scope, I’m going to try to borrow it sometime.
The bolt face was in in the pictures or the description. I have heard of bolt face erosion, but have never seen it, after this, I will always ask for a picture of the bolt face.

 

[K981985]

Bolt face erosion is a little misleading, as if to imply age or number of rounds would normally cause this. Like I mentioned before I have rifles that have shot more than a few thousand rounds and I’ve seen rifles over a hundred years old with military service and who knows what else, non had that kind of bolt face damage. And Damage is what this is no amount of normal shooting causes this. It was a serious event either once or multiple times. I’d definitely have a talk with the previous owner or seller. He may have pawned a serious problem on to you. As mentioned not only the bolt but the barell throat, locking lugs etc. could have been damaged beyond repair. If the lugs were set back not sure it could be easily repaired .

 

[Wyatt Smith]

It was part of an estate on gunbroker. The previous has passed away. I have a new bolt on the way, and will bore scope it when I get the chance.