I've switched a couple 700 barrels in the past and always was able to get the headspace in check by having a decent supply of recoil lugs around.
This time is different, I am installing a 40X barrel and using my thinnest factory lug, I still have around .008 headspace. This is calculated by using shims on the bolt face behind a Go Gauge.
My question is should I just surface grind the lug till I achieve my desired headspace or should I move the shoulder back on the barrel?

I presume you're switching barrels to utilize a cheap source of prethreaded and chambered barrels to save gunsmithing costs? Nothing wrong with that, if you watch what you're doing. Not as good as a quality rebarrel, but can work out very good. Especially if you don't have a lathe and the reamer and a mandrel to square the action on.

Personal preference, I would lap the bolt lugs first, as that will add a bit more headspace, then set the barrel back within about .002 of what I want, then lap the action and barrel using the lug I intend to use and grinding compound.

I put a bit of grinding compound on the action face and on the barrel shoulder, and put the lug onto the barrel. Oil the barrel where the lug rides on it. Now, screw in the barrel till it just snugs against the lug, and rotate the lug with your fingers. Work it backwards and forwards, round and round, and tighten the barrel as needed to keep it cutting. Watch the action face and stop when the wear pattern is even all around the action ring, as that indicates that it is now square with the barrel. Check the barrel for the same. Usually this removes about .002 of headspace. If you don't have a lathe to set the barrel back, you can carefully file a few thousandths away after carefully scribing a setback line, and then lap the barrel square with the lug as I described. It takes a lot of patience, and best to use a scrap lug as it will wear tapered. Do the final bit of lapping with the lug you intend to use to get a good fit.

Poor mans truing/accurizing job. Just another way of getting a bit of extra accuracy out of factory parts on the cheap for a guy without the tooling to do it first class.

dave

Recoil lugs are cheap and easy to replace. Surface grinding would work as long as it is square and accurate. So will setting the shoulder back. If you try lapping things in then you change the setups for your other barrels.

quote:

Originally posted by j*cf:
I've switched a couple 700 barrels in the past and always was able to get the headspace in check by having a decent supply of recoil lugs around.
This time is different, I am installing a 40X barrel and using my thinnest factory lug, I still have around .008 headspace. This is calculated by using shims on the bolt face behind a Go Gauge.
My question is should I just surface grind the lug till I achieve my desired headspace or should I move the shoulder back on the barrel?

Why use shims when taking the measurement? I would just take the measurement directly from either the receiver or the barrel and transpose it to the other. Don't forget to allow for a loss of .002 - .004 when you seat the barrel.

quote:

Originally posted by Westpac:

quote:

Originally posted by j*cf:
I've switched a couple 700 barrels in the past and always was able to get the headspace in check by having a decent supply of recoil lugs around.
This time is different, I am installing a 40X barrel and using my thinnest factory lug, I still have around .008 headspace. This is calculated by using shims on the bolt face behind a Go Gauge.
My question is should I just surface grind the lug till I achieve my desired headspace or should I move the shoulder back on the barrel?

Why use shims when taking the measurement? I would just take the measurement directly from either the receiver or the barrel and transpose it to the other. Don't forget to allow for a loss of .002 - .004 when you seat the barrel.

I was thinking the same thing.
Use a depth mic

quote:

I still have around .008 headspace. This is calculated by using shims on the bolt face behind a Go Gauge

Face the front of the receiver ring back .006.

to add one more thing which you may have checked:be sure by getting the headspace correct you aren't getting the bolt and barrel in contact,i usually screw the barrel in by hand without a recoil lug till the headspace is where i want it, then see how much gap you have before the bolt and barrel make contact.