Gunsmithing Will lapping my lugs F$&@ up my Headspace?

[EastCOYotes]

Title says it all. I’m thinking of buying a remage barrel for a rem 700 action of mine, and considering lapping the bolt lugs when I have the action bare.

The old barrel isn’t worn out, so if I ever go back to using the original shouldered barrel will my headspace be off?

 

[JMGlasgow]

I would just leave them alone. If you're concerned send it to LRI to have the whole thing trued.

Mine didn't make contact on both lugs at first, but with use they now contact very well.

 

[Easy_E]

If the head space is tight on the original barrel and you just do a little polishing to lap the lugs you should be ok.

 

[fdkay]

if your using a remage barrel, you'll set the headspace when you install it. As for the old barrel, depends on how much material is taken off, but after shooting a high quality barrel on it, you'll likely never go back to the original

 

[Deleted member 10043]

Not a bad question to ask. In fact, it is one of the best questions I've seen in a long time. Liberal Arts does result in critical thinking and can be appied to your rifle. Sanding on anything will make something shorter or thinner. But if lapping lugs result in a no go gauge closing you may have lapped way too much.

 

[E. Bryant]

It would take some effort to lap the lugs so far that headspace is affected to the point that it becomes dangerous. But I've seen a lot of effort put into doing silly things.

The better question is: what do you hope to accomplish by lapping the lugs? If the lugs are not flat and square, it is unlikely that lapping will improve matters. It will simply make the bolt and receiver lugs similarly un-flat and un-square.

My recommendation would be to leave this alone. Either do a proper blueprint on the receiver, or let it be and focus on the things you can control (installing a quality barrel and working on load development).

 

[fdkay]

To properly lap the lugs, you'll need a lapping tool and compound. Honestly, I would find a local Smith that can square the receiver face and lap the lugs in for you. Shouldn't cost that much.
The problem with chucking up the bolt and squaring up the back of the lugs and squaring up the lug abutments is that you will almost certainly need to time the bolt.
A gentle lapping won't.

 

[Ledzep]

TLDR: For what you're doing I wouldn't waste your time, money, effort, etc.. lapping lugs.

1. If both lugs make contact (Don't care if it's 10% on one and 40% on the other) understand that lapping the lugs is an exercise in placebo.

2. If you lap the lugs so much that it affects headspace to an unsafe extent, you need to get your OCD meds checked.

As far as blueprinting goes, of the dozens of actions that I've blueprinted, I don't remember any of them where the bolt lugs didn't clean up in the same pass, and only 1 where the bolt face was cut off square. It makes sense because they're turned on a lathe to begin with.

As far as actions, it's a very rare thing for the lugs to be out of square with each other to the point that they truly NEED to be fixed. From a physics stand point as long as both lugs are making contact, the level of elastic deformation that's going to happen during firing is in the .000xxx range, and isn't going to measurably affect precision on target. If you have any test data that shows otherwise I'm all ears.

I've purposely misaligned barrels in the action to look for degredation in precision and haven't found it. In the future I may try some larger sample sizes (I've done 20 round groups so far) in the 50+ range to find the subtle differences in the average, but my gut thought is it doesn't make a difference. Accuracy is in bullets and barrels. Good quality barrels with a decent chamber job get you 95% there, the last couple tenths are in the bullet and load.

 

[LRI]

Title says it all. I’m thinking of buying a remage barrel for a rem 700 action of mine, and considering lapping the bolt lugs when I have the action bare.

The old barrel isn’t worn out, so if I ever go back to using the original shouldered barrel will my headspace be off?

If you use aquarium gravel to lap em, then maybe itll affect your HS.

Lapping anymore isn't much more than a means to verify if you have lug contact on both sides.

If you decide to have the action tuned up we'd be happy to help.

C.