Bore Lapping

H

herbie1

New member
All,

I was curious as to the effects of bore lapping a 4" revolver.

Is there a worthwhile accuracy increase?

Are there any other benefits? (BTW I use jacketed bullets so lead fouling is not an issue).

Are there any cons to a lapped bore in a 4" revolver.

The reason I as is because I think my S&W 686 SSR came bore lapped from the factory. When I look down the barrel the bore has an almost mirror like smoothness/finish to it. Also, the lands and grooves are not nearly as sharp as my other guns (except Glock).

Thanks.

H.
 
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It depends. Some Ruger single actions have a constriction where the barrel is screwed into the frame and careful lapping can cure the ill. I have also seen, primarily on Rugers, forcing cones that are centered properly but rough. The best fix is to have it redone, but again, careful lapping can do a great deal to at least smooth out the part that needs it.
 
I guess i am one that always spends some time with jb's bore polish work'n on a new barrel just to helpsmooth the forceing cone area too and even cylinders on some revolvers.and chambers along with feed ramps. Also always take a extra bit of care checking for any copper deposits in the barrel on a new gun . But not for long.
 
I have not yet tried fire lapping, but I have used JB Borebrite to carefully lap a couple of guns. I did my Ruger MK IIIs and a Bearcat. Only about 6 strokes for each one. I then shot a bunch of copper wash ammo through them. When they got smoothed out, they shot a lot better and didn't metal foul as they did when new.

If you do too much, you just ruin the barrel.
 
Forgive my ignorance, but what exactly is the benefit of bore lapping in general? What does it accomplish, if anything?
 
Unless you are buying a highend airgauged barrel there will be some scrape or mill marks in the barrel or and sharp edges that can be smoothed some as to not pick up lead or copper as quickly. So useing bullets designed for that or like some of us that use a bore polishing compound to do the same job with just a bit more work. Also works on feed ramps and chambers too.
 
Not a bad idea.

Some gunsmiths are doing something called a "Taylor Throat", basically taking the constricting area at the back of the barrel and lengthening it to be about the same depth as the caliber. This helps relieve the constriction often found at the backs of many revolver barrels, not just Rugers.

This doesn't solve the problem of rough bores collecting lead. For that you need to do some form of lapping.
 
If you shoot much lead in your handguns a lapped bore will not foul as readily. I have a Mountain Competition 45 that was diamond lapped by the gunsmith and after a 2700 match two passes with a bore snake leaves the barrel clean. I still disassemble and use a brush and solvent at home but I don't think it is that necessary. Old habits are hard to break.
 
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