Stubborn copper at crown

brmfan · November 2, 2009, 11:56 PM

I have a Remmy PSS that always accumulates stubborn copper fouling right at the last 1/16" or so of the rifling. I use Break Free bore foam which does a great job and I always keep the foam from receeding up the bore but even still I have to go back a few times to get those last little spots.

I've already run the Tubb Final Finish, but I guess the bullets were so compressed by the time they reached the crown the grit didn't have much of an effect. Should I use a tight patch on a jag with some JB paste to polish it out?

**Unclenick** · November 3, 2009, 02:02 AM

Sounds like you have a constriction in the barrel that is squeezing the bullet down before it gets to the muzzle. Get it clean and slug the lightly oiled bore with a pure lead slug. You will be able to feel the constriction pushing it slowly down the bore. A a bonus, you can mic the slug to learn your land and groove diameters.

Your options for removing it are hand lapping and firelapping. The Tubbs system surfaces the bore, but does not cut out constrictions, as firelapping does. Since you've already polished it, though, you will have incurred a little bit of added throat wear and probably don't want to alter it further until it has eroded from firing. Hand lapping will remove less extra metal and largely leave the throat alone.

November 2, 2009, 11:56 PM	#1
brmfan Senior Member Join Date: October 21, 2008 Posts: 557	Stubborn copper at crown I have a Remmy PSS that always accumulates stubborn copper fouling right at the last 1/16" or so of the rifling. I use Break Free bore foam which does a great job and I always keep the foam from receeding up the bore but even still I have to go back a few times to get those last little spots. I've already run the Tubb Final Finish, but I guess the bullets were so compressed by the time they reached the crown the grit didn't have much of an effect. Should I use a tight patch on a jag with some JB paste to polish it out?

November 3, 2009, 02:02 AM	#2
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,063	Sounds like you have a constriction in the barrel that is squeezing the bullet down before it gets to the muzzle. Get it clean and slug the lightly oiled bore with a pure lead slug. You will be able to feel the constriction pushing it slowly down the bore. A a bonus, you can mic the slug to learn your land and groove diameters. Your options for removing it are hand lapping and firelapping. The Tubbs system surfaces the bore, but does not cut out constrictions, as firelapping does. Since you've already polished it, though, you will have incurred a little bit of added throat wear and probably don't want to alter it further until it has eroded from firing. Hand lapping will remove less extra metal and largely leave the throat alone. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle