Truing action: How much total is too much?
- Thread starter Mram10
- Start date
The receiver face amount is not critical. The amount taken off the bolt lugs and the mating receiver faces reduces the amount of available extraction camming and if it is more than a small amount the bolt handle needs to be re-located. Generally, the best amount is as little as possible. If you get out to as much as a combined total of more than about .010 you may also have to compensate for reduced firing pin fall. If you encounter a badly damaged action that needs a lot of material removed you just have to decide when to cut your losses.
Boyd Allen
Active member
The amount taken off of lug abutments comes off of the closing cams.
jackie schmidt
New member
Why would you do anything to the lugs or abutments?
I lap the lugs before doing anything, using a tool The exerts pr sure straight back. When I see good contact, I then true the action up in my Lathe by the boltway and chase the threads untill they are dead true, and take just enough off of the face of the action to make it truly square.
I have no idea why Gunsmiths machine ther parts of the bolt, such as the front of the lugs and the face of the nose. They fit nothing but air.
It might look attractive, but all it does is screw around with things like bolt timing and extraction.
I lap the lugs before doing anything, using a tool The exerts pr sure straight back. When I see good contact, I then true the action up in my Lathe by the boltway and chase the threads untill they are dead true, and take just enough off of the face of the action to make it truly square.
I have no idea why Gunsmiths machine ther parts of the bolt, such as the front of the lugs and the face of the nose. They fit nothing but air.
It might look attractive, but all it does is screw around with things like bolt timing and extraction.
There is no real need to keep things equal. Just remove the very minimum amount possible to straighten things up. After everything is finished, evaluate the effect on extraction and firing pin fall and re-locate the bolt handle if necessary. Some of the new Remington actions have very poor extraction to begin with and need the bolt handle re-located anyway. If you don't want to do this yourself, send the action to Dan Armstrong and have him locate, time, and tig weld the handle after you do your machining.
To fit the barrel, measure the action from the front of the receiver to the bolt face and to the front of the bolt lugs and cut the tenon to allow the amount of clearance you desire.
The firing pin fall is reduced by the amount removed from the back of the bolt lugs and the mating surfaces in the receiver because the bolt position in battery will be farther rearward relative to the trigger. I've never seen one that needed enough material removed to have any significant effect, but if a receiver was really worn or galled enough to require more than a few thousandths it could be a factor. Really a rare instance that it would have an affect.
I'm thinking of it this way. If you remove .002" from the rear of the lugs, the bolt and, subsequently, the firing ping, would be .002" farther away from the case head. You'd have to reduce headspace .002" to compensate. Or, am I just misunderstanding this whole thing? Accurizing is done first so headspace is a non-issue since you'd chamber after accurizing or, at least, I would.
increasing or decreasing headspace does not affect the amount of firing pin fall although excess headspace does reduce the firing pin strike because the pin does not impact the primer to the same depth. The length of firing pin fall is determined by the relationship between the trigger and the cocking piece. If the bolt is moved rearward and the trigger stays in the same position, there is less firing pin fall. For the purposes of truing an action, it is highly unlikely that the amount will be enough to make a bit of difference. Sorry to cause confusion over what is pretty much a moot point.
Isn't the firing pin fall stopped by the cocking piece when it is stopped by the bolt shroud. The only way to change that is to remove material from the bolt face, the cocking piece or the shroud
I think the reason for the confusion is that everyone thinks I am talking about firing pin protrusion. I am talking about firing pin fall: the total distance the striker moves when released by the sear. Moving the bolt rearward by removing material from the lugs and abutments reduces the total amount of travel. As I stated several times, it is very unlikely that the amount (2-3 thousandths in most cases) is enough to make any difference. The amount the firing pin protrudes from the bolt face in the un-cocked position is actually increased by the amount removed from the bolt face; also not enough to make any difference.
For the life of me I don't know why I even mentioned it.
Boyd Allen
Active member
The firing pin is not stopped by the cocking piece, but rather the dry fire shoulder near the front of the pin, the front side of the flange that the striker spring rests against the back of. Also the shroud does not stop anything, it merely guides. If the firing pin was incorrectly modified so that the cocking piece did stop the pin, the place it would hit would be at the bottom of the cocking cam notch at the back of the bolt body.
The TactiKool/ Mall Ninja Crowd & 1K Bench Rest crowd seem to think firing pin fall has to be 1/4" minimum for consistent ignition of our current 3 legged anvil primers.
To the OP-
Hopefully you are practicing on your own equipment before you hang a shingle out for services offered/performed.
Your HS gauge inquire was answered on 6mmBR but you acted otherwise w/ a piece of brass. DUH!!
To the OP-
Hopefully you are practicing on your own equipment before you hang a shingle out for services offered/performed.
Your HS gauge inquire was answered on 6mmBR but you acted otherwise w/ a piece of brass. DUH!!