Gunsmithing Headspace issue - what are my options?

[atxhorn4425]

Hey guys - as part of my efforts to revitalize a Remington M700 that was passed down to me, I decided to use my (very) amateur gunsmith skills to square up the bolt and receiver lugs by lapping them, I thought gently. According to the Dykem, before the lapping there was very little lug contact on lockup, afterwards there was maybe 90% or a little more..

Now I’ve got unmistakable pressure signs using two different kinds of factory ammo. Pretty clear to me that I’ve messed up the headspacing. Turning to SH’s collective wisdom, do you agree with the diagnosis, and what are my options to correct the problem? Which I will very obviously be having a professional gunsmith do this time

Thanks in advance!

 

[dimar1492]

Which pressure signs are you seeing?

Need to verify that headspace is excessive by some form of measurement be it guages or the scotch tape method.

If in fact headspace is excessive you could just skim a few thousandths off the shoulder and breech to close the gap the appropriate amount.

 

[atxhorn4425]

Flattened and cratered primers, some case head discoloration, extremely difficult bolt lift in two different loads.

Sounds like a pretty easy fix, thanks!

 

[Wannashootit]

Assume you'd fired the rifle before you decided to pull the barrel to lap the lugs (and didn't have any issues)?
You'd need to remove a lot of metal to take from tight (go+0-1) to beyond no-go, and you say you don't think that was the case.
Wondering if the chamber wasn't cut too deeply to begin with, or possibly a really high round count had set back the lugs.
Is this a magnum, and what do you know of the history of this "hand me down"?

 

[atxhorn4425]

It’s a 7mm Rem Mag, Model 700 Sendero. It was my dad’s, not a particularly high round count rifle (I’d guess maybe 200-300 tops), but not well maintained. Had certainly been fired by me before without any issues.

I actually didn’t remove the barrel when I lapped the lugs, which may have been a mistake. Just put Dykem on the rear of the bolt lugs, used a small dab of lapping compound and cycled until I had about 90% contact, then swabbed the crap out of the chamber.

 

[supercorndogs]

Did you get all the oil out of the chamber? Cratered primers I would expect on a 700. Heavy bolt lift is bad.

 

[DAVETOOLEY]

You can't lap the lugs flat and perpendicular to the action bore the way you did it. You took a high spot and lowered it while making a corresponding low spot on the the other surface. That's what's causing your hard bolt lift. Lapping mates two correctly machined surfaces together.

 

[fdkay]

Listen to Dave.
You can't shortcut something like that, which is why they make specific tools for it.
http://pacifictoolandgauge.com/remin...ping-tool.html
Even the tools can fuck it up is stuff isn't square, which is why most put them in a lathe.
Any time you remove metal, you increase headspace, not usually enough with minor lapping
You may be better off buying a new bolt, hopefully you didn't trash the action

 

[atxhorn4425]

Thanks for the tips guys. Definitely won’t be doing that again. Will be sending to my gunsmith shortly.