Home Forums Hunting & Shooting Gunsmithing Barrel lapping

I’ve got a rifle with a douglas barrel I had built nearly 20 years ago that copper fouls horribly. It shoots great until it fouls. I’m thinking of trying to lap it just a bit to see if I can get it to stop the fouling. I’ve bought some lapping compound and asked my Plummer buddy for some pure lead…. Any pointers before I start? The lapping coumpound kit I bought comes with 4 different grits…. Can’t remember but I think 220-800… I think.

Thanks in advance.

Ben

Just shoot the hell out of it and keep mining the copper until it straightens itself out. Also to add, of all the barrels that I've dealt with, Douglas have been the worst in straightness and accuracy. I've had more Green Mountain barrels that were near perfectly straight and will shoot bughole groups than any other brand. Just installed a McGowen today that was contoured and threaded between centers by the company but had the chamber cut the proper way.

This seems a lot easier to me...

http://www.davidtubb.com/final-finish-bullet-kits

I did something similar with a NECO kit to a really rough Rem. factory barrel many years ago & it still cleans almost as easy as my premium barrels. The only down point was the throat lengthened about .020" or so. Not a bad trade off.

Green Mountain winning a lot of benchrest matches? F class?

Not sure on that. I've built quite alot of benchrest guns with that moniker that will shoot unbelievable groups but im not aware of which benchrest classes they're being used in but im wholeheartedly impressed with Green Mountain.

Douglas does not lap barrels as most others do, and they can foul. The makers that do lap, use a compound in the 150-180 grit range. Finer grit actually will foul worse. Since your barrel is already chambered, the leade will change. The fire lapping will definitely move the leade forward. If you can deal with a longer seating depth, then fire lapping can help. I would use a cast bullet at a slow speed.

Shooting the hell out of it won't stop copper fouling. Once copper is laid down, the next bullet will add to it. That's why when people break in a barrel, it's a one shot and clean until the copper is gone, then shoot another.

^^^^^^^^^^^^^^^^^^^^AGREE^^^^^^^^^^^^^^^^^

Wayne's advice is spot on.

Not sure what lapping compound you have but aluminum oxide does a much nicer job than the silicon oxide. Stan Ware taught me how to lap and that was his approach...150 grit aluminum oxide mixed with a thin grease. It breaks down into a nice soupy mixture that's not super aggressive. I've done a few factory barrels this and it always brought the fouling around. Recrowning is a must after lapping.

FWIW, Dyna Bore Coat has has settled the fouling down on a vintage Savage varmint barrel that I have. If you want to tiptoe into fixing the fouling and not have to recrown, it might be a worthwhile first step to consider. I've been impressed with the fouling reduction in two other barrels I've used it in as well.

For what it's worth...-Al

Thank you for everyone’s input. I already tried the dyna bore coat. I may give it one more try. I’m getting pretty tired of cleaning the hell out of this barrel. I hadn’t thought about having to recrown the barrel afterwards. Makes sense though.

Listen to Wayne Shaw. I've never known a barrel maker using finer than 240.

Butch, Stan had a bunch of 40X new barrels from Remington. I remember one that he lapped with 240. I did the load work on it...that thing laid down copper like you wouldn't believe! He relapped it with 150 and it came right around.

Shot great laying down copper until about 50 rounds. After relapping it would go 150 before needing any attention.

Good shootin' -Al