Lapping a Barrel

[fredhorace77]

Just how do custom barrel makers go about lapping a Barrel?

 

[watercam]

From what I have gleaned, they run a rod and Jag into the barrel just short of the far end, pour molten lead onto the jag and allow to cool. Then push the jag/lap out of the barrel just enough to apply lapping compound to it without it leaving the barrel (so the bore lap is still engaged with the grooves). That's the easy part. Next they run the lap back and forth until the bore 'feels' right. It is an art.
FWIW I have lapped factory barrels (and one or two 'custom') by wrapping a patch around a slightly undersized brush coated with lapping compound to remove light tooling marks left by who ever made the barrel in the first place. On one occasion I had a barrel rebored only to find out that the 'barrel maker' had not stress relieved the barrel after boring and rifling. Seems he 'never had to with sporter barrels'. Had it cyrogenically treated by 300º Below and it has been my Palma barrel for a season so far.
No end to the mischief one can get into with firearms!

 

[hoz53]

Just how do custom barrel makers go about lapping a Barrel?

Do a search here-- there was a guy who provided good info and pics on how to do it awhile back in the forums.

 

[fredhorace77]

Thank you for the info. I've also got a couple factory barrels I would like to lap. I have considered just purchasing the Tubb kit, but I hate to shell out that much money. I was hoping I could lap the barrel with some lapping compound and a couple patches on a jag.

 

[Alex Wheeler]

To lap any hole you need a lap. The lap will only work the tightest parts of the bore. You occasionally recast the lap until the bore is uniform. If you use anything else you defeating the purpose of lapping, to make the hole uniform. A patch will not uniform anything, and it will not give you the feedback required to know where the bore needs lapping. Lapping compound on a patch is a bad idea.

 

[fredhorace77]

To lap any hole you need a lap. The lap will only work the tightest parts of the bore. You occasionally recast the lap until the bore is uniform. If you use anything else you defeating the purpose of lapping, to make the hole uniform. A patch will not uniform anything, and it will not give you the feedback required to know where the bore needs lapping. Lapping compound on a patch is a bad idea.

Ok thank you

 

[Kurz]

You also need to be aware of the lap at the muzzle since in many cases you will find that there is an imparted wiggle to the lap from the length and diameter of the rod being used. This will actually enlarge the muzzle making the barrel less accurate unless you cut off the last inch or so of that barrel. This is the recommended procedure offered by barrel makers when shipping blanks.

 

[bugman]

good lapping and lap-casting technique takes a long time to develop. add in a little art with the science. it is usually a bad idea to lap after chambering. depending on the caliber, a little choke at the muzzle is a good thing....if you know how to "feel" it. etc, etc, etc..

the point is that trying to lap those factory barrels is probably not a good idea unless you are set up and experienced enough to attempt it.

 

[fredhorace77]

good lapping and lap-casting technique takes a long time to develop. add in a little art with the science. it is usually a bad idea to lap after chambering. depending on the caliber, a little choke at the muzzle is a good thing....if you know how to "feel" it. etc, etc, etc..

the point is that trying to lap those factory barrels is probably not a good idea unless you are set up and experienced enough to attempt it.

Ok thanks for the help and info

 

[Liven The Dream]

I have used Krieger Barrels break-in as posted on his web. page.
Then used JB add a good cleaning on His and factory barrels.
This has given 99% results .Had a Ruger #1 in 257 Roberts nothing work even had it lapped by Obermeyer Barrels.
Best off Luck