Gunsmithing Shouldered barrel reinstall
- Thread starter Boatninja
- Start date
Scribe a witness mark on the barrel and action, I usually do it 6:00 underneath and onto the recoil lug prior to removal..... upon re-install simply torque it to where the scribed lines line up....it will be surprisingly consistent...... you can check it with the gauges but I'll bet you if it's within spec prior to removal lining up the marks will put it back Exactly the same.
A scribe mark is not going to give you a repeatable torque value on that big of a thread. The thickness of the recoil lug sets the headspace, the torque keeps the barrel from backing out. Just make sure she's purdy tight, you'll be ok. With people using everything from 30-100FTLBS the workable range seems to be wide enough its not worth stressing over anyway. But 30-100 is not what would change the headspace. Changing the recoil lug or the action the barrel is on might.
There's a number of ways to change headspace, just ask any novice barrel turner. Usually, it's set by the tenon length at the shoulder. Headspace will shrink about .002" at about 100 ft/lbs (generally called "thread crush", but it's more like thread stretch).
I do think you'll get reasonably close by @cwinner suggestion using an index mark. If you using an exterior action wrench, you're estimating the torque anyway. Use some anti-seize on the threads, screw it back in, and tighten it up until your witness lines match up.
I do think you'll get reasonably close by @cwinner suggestion using an index mark. If you using an exterior action wrench, you're estimating the torque anyway. Use some anti-seize on the threads, screw it back in, and tighten it up until your witness lines match up.
We aren't talking about turning barrels, we are talking about removing and reinstalling a shouldered barrel. You are going to get a more accurate torque from feel than a witness mark. Lean on the wrench and grunt, a witness mark is going to be more or less useless on shouldered barrel. Between the time the shoulder contacts the lug and its torqued, from 30-100ftlbs its not going to move.
I do it all the time. I have practice barrels that I will swap on and off. Torqued to the same ft/lbs everything repeats including zeros. Go / Nogo is probably a good idea but it should not change unless the mating surfaces have debris on them or the torque wildly changes.
It’s like pulling a bolt and putting it back in.
lube the threads, slam it home and torque her up.
lube the threads, slam it home and torque her up.
The main difference with a bolt being, a 1 1/8" grade 8 old is going to be torqued to 644 lubed or 1287 dry. Relative to thread size, the torque used to tighten barrels is very low.
