Lapping bolt lugs

[chalmitch]

Is there a good smith in SE PA to lap the lugs on my .223?

Thanks,
chalmitch

[SteveWag]

What rifle and why?

Steve Wagner

[chalmitch]

Rem 700 and looking for perfection.

[SteveWag]

OK,

Assuming that you either reload or have a No-Go gage it's pretty easy. Most lugs are lapped with the barrel off the receiver and when the barrel is (re) installed the chamber is cut to achieve proper headspace.

In your case I am assuming you can live with the increased headspace. First, using cold blue, blue the mating surface of the bolt lugs, put a LITTLE 400 or 600 grit grinding compound on both lugs, both surfaces. Insert the bolt and close while holding the bolt forward. Put a cleaning rod down the barrel, put the butt against you stomach and press the rod handle against a wall, exerting a little pressure. The intent is to force the bolt back against the lugs. Work the bolt handle up and down, but don't open the bolt, just rock the handle. After about ten rocks, remove the bolt and inspect the blueing. If some buleing remains, try again. Sometimes it takes 20 min. or more. You may want to check headspace every other time.

Steve Wagner

[Tomcat088]

Hmmm, I must say, that's an interesting way to true up some lugs. I was figuring that since he was asking about a gun smith he wanted someone to chuck it up in the lathe. I can see how your technique might polish them up and work, but if the lugs were way out of true man that would take forever. I'd be real careful forcing a guide rod against the bolt face though, I'm sure you could really make things ugly that way or if you were pointing the muzzle down you could damage the firing pin. Either way, I'm not from the area, so I know of no smith's to help you chalmitch.

[SteveWag]

Lapping is done just the way I described, but with the barrell removed and a spring loaded plunger holding the bolt back. See this:

http://www.gswagner.com/bob/bob3.html

A lathe will not do this kind of job. The idea is to take two very well matched pieces and "lap" the mating surfaces till the parts fit exactly. In a two lug bolt, both lugs must share the chamber pressure equally for maximum accuracy.

The pressure exerted on a cleaning rod is not enough to damage the bolt face, and if the rod rotates, then there is no bubbing on the bolt. The only danger is that stray grinding compound may get onto the wrong items, but this can be controlled.

The title of this Forum is:

"Gunsmithing If you're the kind of person who likes to do things yourself, this is the place for you"

Steve Wagner

[Tomcat088]

Lol, you're crazy if you think a lathe can't true up lugs Steve, although you're correct that is how "lapping" is done. I'm pretty sure that he wants them "true" and has just heard alot of people talk about "lapping the lugs" otherwise he could do it just the way you mentioned and wouldn't need a gunsmith. Every "true" custom rifle that I know of that has been blue printed and had the lugs "trued" has it done in a lathe. I realize that you want the surfaces to mate exactly and that they need to chare the pressure equally. If the surfaces were that far out, they would actually not even fully lap out to meet equally, but they still probably wouldn't be "true" just at the same angle and mating. By turning it in the lathe, you can actually true up the surfaces so they exactly match and then polish them up if you like. You have to be careful with this though, because if you don't have a gunsmith who knows what they're doing they'll get the bolt out of timing and you'll loose all your cam or won't be able to tell the true headspacing on the bolt because it will be resting on the back of the bolt handle.

Either way I wasn't trying to pick a fight, just trying to make sure that the OP is getting what he wants. You are right, what you mentioned is "lapping", but the lugs can be trued up so the surfaces mate exactly true in a lathe. If you would like I can post up a video of the process being done.

[Pukindog]

Chalmitch if you are looking for perfection lapping the lugs will not do it. Take the rifle to a very competant smith and have the action blueprinted and trued. Only way to get "perfection" in my book.

Jeff