Bolt lug lapping?

[IWAC]

I have read, mostly in older gun journals, that lapping the lugs in almost any bolt-action gun can improve accuracy.

I'm wondering if my Ruger MK II bolt gun would benefit from the procedure?

If so, how can it be accomplished without having to buy a rather expensive tool that will in all likelihood, only be used once?

Midway USA to carries the tool, but only for Mauser 98 large ring and Remmie 700 actions. I watched Larry Potterfield's YouTube presentation, and it looks fairly simple. (Famous last Words!)

Thanks

 

[Kp321]

Lug lapping doesn't hurt but it might not help much either. Before putting a lot of effort into lapping, check to see if the lugs are already bearing evenly. If both lugs are seating fully, lapping wont help anything. You can look at the wear pattern on the back face of the bolt lugs and tell a lot. Another check is to color the backs of the lugs with a Sharpie and close the bolt holding back on the handle. You can see the seating area where the Sharpie is rubbed off. It one lug is clearly not bearing, proceed with lapping. I use 240 grit till I get good contact then work up to 500 grit for polish, cleaning everything well between grits. You don't need a tool, just pull back on the bolt handle while working it up and down. Check and put fresh compound about every ten cycles, the grit wears and quits working unless renewed.
Probably more than you wanted to know.

 

[dsink]

Be careful doing it. You might set your bolt back to far and open up your headspace to an unsafe point.

 

[Taurus 617 CCW]

I had a guy ask me how to lap bolt lugs. I laid out a set of instructions for him to follow but he forgot the step where you check how much contact between laps. He also used 220 grit for the entire process. He ended up with a bolt that would self open by giving it a light tap from underneath! Dead receiver and bolt.

My word of advise is to understand the process completely before starting. You should know how to do it in your sleep before attempting. It also makes things easier if the barrel is not screwed into the action but that is more difficult for most folks to do. You need a lathe or barrel vise and have to re headspace the action when finished.

 

[IWAC]

I had a guy ask me how to lap bolt lugs. I laid out a set of instructions for him to follow but he forgot the step where you check how much contact between laps. He also used 220 grit for the entire process. He ended up with a bolt that would self open by giving it a light tap from underneath! Dead receiver and bolt.

*****
WOE! That is not what I am looking for! I had wondered about that. Thanx!
*****
Lug lapping doesn't hurt but it might not help much either. ... check to see if the lugs are already bearing evenly. Another check is to color the backs of the lugs with a Sharpie and close the bolt holding back on the handle. You can see the seating area where the Sharpie is rubbed off. ...Probably more than you wanted to know
*****
NOT! That was exactly what I needed to know. It was a "Why didn't Ithink of that" moment. I did the Sharpie thing, and the lug contact looks to be about 70-80%... good enough for any reasonable purpose, sez I. For once in my life, I will avoid the "If it ain't broke, give it here for a minute" syndrome. The lugs will wear in more with normal use, and I'm not gonna mess with it!

Thank you all very much!

 

[dfariswheel]

Master gunsmith Jerry Kuhnhausen in his shop manual on the Mauser rifles said that lapping to 100% contact was not a good idea since that was likely to break through the surface hardening.
As I recall, anything around 50% contact is plenty.

Most lapping is best left to un-barreled actions so after lapping you can set the correct head space when installing a barrel.

 

[rcmodel]

What he said!!

Lapping the bolt lugs After the firearm was barreled & the headspace has been set is a sure way to increase the headspace.
Perhaps beyond acceptable limits.

So, Don't.

rc

 

[Jim Watson]

Lapping in locking lugs is typically just one part of the "blueprinting" package that is done along with installation of a new barrel. Can't see it being worth a lot on a factory gun.

 

[triggerman770]

What Jim Watson said. If you just lap the lugs(and this is mostly done on match rifles) and do none of the other blueprinting measures you won't notice
any difference

 

[IWAC]

Lapping the bolt lugs After the firearm was barreled & the headspace has been set is a sure way to increase the headspace.
Perhaps beyond acceptable limits.

So, Don't.

rc

I won't!