Gunsmithing Lapping questions

[desertrat1979]

I just checked the contact area on my 700. Needless to say, the one lug (left) barely has any contact. A little bit on the outter edge, and thats about it. Can I lap the lugs w/o removing the barrel? And how much of an effect can this have on headspace? Being money is tight, I figure I will try to do this myself, in addition to re-crowning the muzzle. So, how bad would I run the risk of fucking this up?

 

[skinnj1]

Re: Lapping questions

The question shoulf be am I confidant that I can lap with the barrel on and not cut a tapered mating surface between lugs and reciever abutments. When you use a spring loaded lapping tool it helps keep even pressure on both lugs as you lap mating surfaces. Technique (how and where forces are applied) matter on this on

 

[my human host]

Re: Lapping questions

It can be done. I don't recommend it if you can avoid it.

Like the previous poster said, the real danger is lapping a taper on the on the mating surfaces. When I first started messing with guns, I made that mistake a time or two. I've always found it difficult to get a gun to shoot consistantly with max loads if there is any sort of taper on the locking lug surfaces.

When I screw a gun together, It shouldn't take any more than a minute of lapping to get a nice footprint inside the action. If it does take longer, I start looking for mistakes I might have made.

The effect on your headspace is going to depend on how close to min. you are before you start.

Could you post a good pic or two of your locking lugs? Lapping may not be necessary.

 

[MikeeBooshay]

Re: Lapping questions

Um,,,, before you touch it, how is it shooting?

Stock 700 barrel, untrued action, flexi-flyer stock? If so, if you're under a MOA, the lugs ain't the problem.

Ever heard of the Hippocratic Oath? "first, do no harm....."... Might apply here. If money is tight, leave it alone, you might just cause yourself to need to spend a whole lot more.

 

[DAVETOOLEY]

Re: Lapping questions

Lapping only mates the surfaces together. Without machining all the surfaces involved first you are taking a high spot on one side and making a low spot on the other side. Generally you won't get 100% contact or anything close to it.

 

[MikeeBooshay]

Re: Lapping questions

Dave, that is what I was getting at.

If he laps it, it won't fix, it might increase the headspace enough to cause a couple other issues. At that point he will have to go ahead and spend the money to true up the action and rechamber. Well, if you are going to rechamber, might as well buy a barrel... etc..... and there went 800 bucks...

And if the rifle was shooting within it's limits already... money spent for no real gain. I'll bet, although I do not know the OP, that $800 bucks worth of ammo and training, would produce more real results, than a full up custom rifle.

 

[desertrat1979]

Re: Lapping questions

Well, I found quite a few articles yesterday, and came to about the same conclusion...no lapping. I will leave that as a last resort after everything else is exhausted. It doesnt shoot bad. Its the factory sporter barrel. When I said money is tight, I meant I cannot spend on a blueprint/barrel job right now. It shoots about 1" to 1-1/4". It had a rough beginning, as I did everything wrong in regards to cleaning habits, and it was long term before I found out I may have been hurting the rifle. I will probably have to have the rifle borescoped to see if I had done any damage. I am just looking to squeeze what accuracy I can prior to the barrel tossing in the towel. Its an 06 with just over 3k rounds down the tube, about half that is handloads, which are on the warm/hot side.

 

[MikeeBooshay]

Re: Lapping questions

I think the barrel/rifle is probably shooting about where it should be, given what it is, etc. Save funds, heck, why borescope it? I borescope very large turbine engines, I tell my customers, don't look inside, unless you are ready to spend money and are just looking for justification for it. Borescopes, USUALLY, show more than is really there, exagerated results frequently. And after you spend the bucks to open it up... then what?

Better to save the money, and maybe either trade up later, or have a solid plan to upgrade your existing stick.

Or... do like I told the family law mediator during divorce #2 - " what did I do with all the money I made????? spent most of it on whiskey and women.... the rest I just wasted!!!!