So I chambered my first rifle this weekend and I have a headspacing question. Before torquing down the barrel the bolt would close easily on the GO, but not on the NOGO. With a piece of clear tape on the GO gauge it would close but with a little resistance. With the brass, it closes freely with no tape, a little resistance with one layer and won't close with two. After torquing it to 100fp it will close on the brass with no resistance, one layer of tape gives a little resistance and the GO gauge will not close. This is on a 7mag with nosler brass. The tape measures 1.5 thou on my mic. I'm worried about it not closing on the GO gauge. Thoughts?
Gunsmithing headspace
- Thread starter TRTAC
- Start date
Sounds like you have the go gauge to check this.
Edit to say: Sorry, I re read your post and understand now, that it will not close on the go. When you torque your barrel, you crush the joint and lose from .001 - .002 headspace. Sounds like you had anough crush to give your chamber negative headspace. In most cases you would need to cut another .001 - .002 chamber depth to make up for this crush. Belted cartridge cases are usually under sized from the factory. Because of this, I usually chamber on the go or very close. Based on what you said, I would leave it as is.
Edit to say: Sorry, I re read your post and understand now, that it will not close on the go. When you torque your barrel, you crush the joint and lose from .001 - .002 headspace. Sounds like you had anough crush to give your chamber negative headspace. In most cases you would need to cut another .001 - .002 chamber depth to make up for this crush. Belted cartridge cases are usually under sized from the factory. Because of this, I usually chamber on the go or very close. Based on what you said, I would leave it as is.
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That's the crush everyone talks about when you torque a barrel down. If you want to open it up more you can throw an extension on your reamer and turn it a hair by hand. Personally I wouldn't worry.
If it's for yourself no problem. You can understand what was done and adapt for it. If it for a customer it could cause an issue of where some brass may not fit or on a non belted case he won't be able to size it back far enough to close easy. Most brass is significantly undersized when new so really it shouldn't ever be a problem that way.
When smithing for the public it's best to stay inside the lines because if there is an accident you can almost be assured if something is out of spec it will be assigned some blame.
When smithing for the public it's best to stay inside the lines because if there is an accident you can almost be assured if something is out of spec it will be assigned some blame.
Yes I have a set of GO/NOGO gauges from PTG. This build is for a personal friend of mine who is an avid shooter/reloader so he should be able to wrap his mind around what is going on.
By inside the lines you mean a GO/NOGO set and not brass right? Another question - will the case/web stretch from multiple firings enough to where the belt will touch? Does that make sense? If it fits now will it fit after being re-sized three times?
By inside the lines you mean a GO/NOGO set and not brass right? Another question - will the case/web stretch from multiple firings enough to where the belt will touch? Does that make sense? If it fits now will it fit after being re-sized three times?
Yes on the gauges. Rarely will the belt itself ever swell enough to cause a problem. A belted case will eventual swell right ahead of the belt where the full length die can not size it and it will eventually stick in the chamber. Minimum head space doesn't really help that. It doesn't hurt it either. Just something to be aware of. This issue usually crops up when a guy comes in for rebarrel. Remington factory chambers are over Saami spec and his brass will be swollen to that spec. You cut a new Saami spec chamber and the old brass sticks in it.
Using brass to gauge head space is useless. It's waaayyyy out of spec for a chamber and too soft to be gauging off of.
Using brass to gauge head space is useless. It's waaayyyy out of spec for a chamber and too soft to be gauging off of.
Run with it! Worst case is something might not chamber but I doubt it. Prob child I'm dealing with made me measure case belts. Federal brass and only one measured .220 on one side. (go gauge) the worst was .212".
Better to have him cry about hard bolt closing than flat primers ;-)
Better to have him cry about hard bolt closing than flat primers ;-)
