I want to get this done to my rifles if you guys think it is worth it. Also, how much does it generally cost to have this done?

Why?
What rifles are you shooting?

I'm going to guess truing a boltface is getting it square with the axis of the bolt, that is, to remove any cant or off-angles from the centerline of the bolt. This will ensure the head of the case thrusts back completely over the boltface and not just on one edge. I am also going to guess it goes a long way toward precluding the bolt getting cocked in the locks and being hard to turn and retract. But what do I know? I ain't no gunsmiff...

As to the why, I guess it takes out another variable that could be causeing a problem in accuracy.
What am I shooting - a Win 70 300 mag and a browning abolt 300wsm

As homebrewer described, its a procedure to make the boltface exactly perpendicular to the bore. It is but one part of "truing" an action, a part that will necesitate setting back the barrel and recutting the chamber to set headspace.

How much does it generally cost to get this done?

I have done it on the Mauser projects I have built but always before setting final headspace.

Why do you want to do this? If you are having accuracy problems, there are a dozen or more things I would do before working on the bolt face.

Help us understand what issues you are having and you will get plenty of excellent advice.


Regards,

Dan

quote:

Originally posted by MRAMSAY10:
I want to get this done to my rifles if you guys think it is worth it. Also, how much does it generally cost to have this done?

I paid to have two centerfire hunting rifles done when I was younger and dumber thinking it would improve accuracy. As far as I could tell it did nothing.

However, if you are having a rifle rebarreled then it might be worth the extra cost (guessing about $100) if you are building what you are hoping will be a super accurate long range varimter or something to that effect.

Before you "true" the bolt face measure it to see if it is out of square. You can do this in a lathe between centers using a "last word" indicater. I find most are square and don't need any machining.....Tom

Tom,
How do you hold it between centers?
Butch

quote:

Originally posted by Tapper2:
Before you "true" the bolt face measure it to see if it is out of square. You can do this in a lathe between centers using a "last word" indicater. I find most are square and don't need any machining.....Tom

Tom,
Can you describe this setup for me? I'm having some difficulty visualizing how one could indicate the bolt face with the bolt "between centers". If the bolt is between centers and supported on the firing pin hole, there is the potential for the hole to be eccentric to the body and cause run out. In this case, indicator results would be meaningless. Regards, Bill
A bolt face which is not square to the body has very little effect on accuracy but can have a significant effect on case life if the error is significant.
The worst case I saw was a Remington 700 in which the bolt face was out of square by .003". Case life was poor and extraction was difficult. Re-cutting the face cured the problem and headspace was corrected by turning the barrel in .003".
Usually, any error in the face is corrected with the removal of less than .002" of material and headspace is likely to remain within spec.
If the face is square to the bolt body but the locking lugs and/or seats are such that the bolt is misaligned within the receiver, bolt face truing is of little benefit. Still, a boltface which is properly machined is probably better than one which is not.

quote:

Originally posted by MRAMSAY10:
How much does it generally cost to get this done?

It is included in my charge for rebarreling which is $230 plus $40 for extractor cut. Can't really square boltface without re-setting headspace which means setting back the barrel. I'd say a reasonable charge for just squaring boltface and setting headspace would be around $150.

No great point in squaring the boltface if the lugs & lug abutements arent also square.
sometimes lapping is enough, other times things may need be set up for machining; = several extra dollars.
When rebarreling best start from scratch,...
true action face, recut action thread concentric, combined with well matched barrel thread.

If you "Truing" the bolt face, does that mean that the cartridge is held straighter in the chamber than if you did not "True" the bolt face?

quote:

Originally posted by butchlambert:
Tom,
How do you hold it between centers?
Butch

Butch,
I machine a plug in the 3 jaw that is a tight slip fit in the bolt, about one inch. I use a small center in the firing pin hole. I then compare the face wobble on the bolt face and the lugs. I understand that the firing pin hole may not always be on center. The amount that the pin hole is off is extemely small compared to the length of the bolt. The amount of face wobble this would induce is .0001 or .0002 at most. What I'm really looking for is the face to the lugs. If the face appears square and the lugs are out a few thousands, machine the lugs. I have found the face square and the lugs out much more often than the lugs square and the face out. In either case it's been very small most of the time. After truing the lugs in both the receiver and the bolt it only takes a small amount of lapping to get 85% (near complete) contact. If I have to machine the bolt face I face grind it square with a tool post grinder. Simular set-up, but no tail stock center......Tom

I'm gona have to say just truing the bolt face wont do any good at all. The bolt face is just one of several areas that have to be square in the action. When the round goes off on a perfectly sqauared bold face but a not perfectly squared lug, the bolt will flex. This makes the "perfect" bolt face not square again as the bullet leaves the case. Lets assume the bolt was held in an adjustable jig, dialed in with two indicaters so its perfectly strait, and the lugs and face of the bolt are cut perfectly strait. Shot another round off and the lugs on the bolt are still gona flex because the odds of the lugs inside the action being strait are pretty slim. So the bolt is still gona flex. So lets take the perfectly squared bolt out of the action, take the barrel out of the action, install the action in an adjustable jig and dial it in with a test bar in the bolt raceway so its perfect. Now lets cut the lugs in the action so there perfectly square. Now lets assume you put it all back together and shoot another round through it. You've pretty much eliminated bolt flex since everything thats touching the bolt is square but now the action face still isn't perfectly square with the action lugs, bolt lugs, or the bolt face. So now when the round goes off, theres no flex in the bolt area but now the bullets not leaving the case perpindicular the bore axis. It might be close, but its not perfect. So lets take the gun back apart and assume we can dial the action back in exactley like it was when we did the action lugs. Now we can face the action which would make the face square with everything else. Screw the barrel back on and guess what, you can fit a .002 feeler guage between your perfectly squared receiver face and you barrel shoulder, why?? because now everything on the action is square but the threads. So lets take it all back apart, assume again we can dial in the action exactley the same as the first time, and lets recut those threads. Now everything on ;the action: bolt face, bolt lugs, receiver lugs, action face, and action threads are perfectly square with the centerline of the action. Now your barrel threads are to small and your factory barrel is useless. I guess my point is this. Theres alot more to really accurizing that factory hunting gun then just taking the bold out and making a couple cuts. When I work on an action, I tell the customer its all or nothing. And I only work on the action if there installing a new unthreaded barrel blank. In my mind if I did just square the bolt face and the guns accuracy didn't improve, even though I told the customer thats what would happen, I would still get the bad rap.