Home Forums Hunting & Shooting Gunsmithing Opening bolt face?

I have some machining skill and machines available and may want to open a bolt face from -06 to Magnum size. (no mag. bolt head available) Is there a method one of you smiths would recommend to accomplish this?


Guess I'm thinking now that even a small boring bar would be to big to use a lathe, so thinking using a mill is the way to go.

I use a little Circle brand boring bar for that type of work.

I ain't no gunsmith, but...

Mandrel for back of bolt.

Steady rest for the front.

Custom ground(by me)tool bit.

Brainless method.
Don

Thanks all

I'm thinking McCray's description would look similar to Malm's with a difference being the cutter.
I'm guessing DonMarkey is pulling my leg a bit or his bolt head needs little rim.
It's good info, both informative and precaution about qualifications/precision.

On our Mausers we have a machines bushing that threads into the action.

The bugging encompasses 2 ball bearings

Through the middle is a custom ground end mill

We do it In a vise with a cordless drill and a mic.

Nope 1909 mauser bolt being converted to .416 taylor. The cutter is from PTG, they make a bushung to insert in the receiver to allow you to use a hand drill, but I'm too cheap to by one.
Don

Excellent thread. Nice to see some real pros giving advice instead of all the "mine is bigger that yours crap" that so many threads quickly turn into.

Congratulations !

The bolt face on some of the older Mausers is estremely hard. Wouldn't you need a carbide cutter for one of those?

I use a carbide boring cutter and set the bolt up on a madrel and in the steady. Same as Malm. GD

I use carbide on the Mausers and High speed steel on the Mosin Nagants.

Yes you need carbine or aneal and recarberize. Here's the carbide bit I use.
http://www.midwayusa.com/product/712896/ptg-bolt-face-truing-cutter-magnum-bolt-face-537-carbide
Don

One thing you want to make sure of is to not take away too much off the bolt face. I have had a couple of guys do bolts for me where they thought it would be good to "even up" the bolt face. They evened it up alright, but the cartriges became, for lack of a better description, "SLOPPY" during cycling.

I had a 'smith tell me he'd not open a mauser to mag b/c in so doing it'd remove the hard skin and over time increasing headspace would occur due to set-back.

With the many mausers that became mags of various sorts I gotta believe this guy was being overly cautious?

I always thought set back had to do with the locking lugs and their seats.

Mauser hardness is skin deep and has no measurable effect on strength.


I have opened the bolt face for belted magnum and tested at up to 107 kpsi chamber pressure.
The bolt body gives behind the lugs, but at the bolt face.

"The bolt body gives behind the lugs, but at the bolt face."

Hi Clark. Good to see you.

Would you clarify that statement. Should the word "at" be changed to not?

Yes, you are right.

I think I remember your handle from years ago at AR. I am trying to keep my memory working by biking a different route every day. Three days ago on a road I was unfamiliar with, I was bitten by a dog.

It was a dumb dog, and I may have been infected with dumbness.

The bolt body behind the bolt lugs will expand a few thou.

The lug abutment orifice in the receiver will constrict a few thou.

The bolt face does not change.

Clark

I definitely remember you. Always great posts about the strength of 98 Mausers. I really enjoyed them.

Looks like a pretty nice dog to me. Are you sure he bit you?

Yeah, I have been dumb for 3 days.

I overloaded a 1903 Turk Mauser with Berdan primed brass.
The case head failed, and pieces of the extractor came back hard toward the shooter. Luckily my face was not there.

So Mausers are strong, but if a Berdan case head breaks in half, you will wish you were shooting a Ruger #1.