My 257 Roberts is reasonably accurate, but the barrel must be very rough, because it picks up metal fouling like you wouldn't believe. I was ratting through my stuff, and found an LBT fire lapping kit I bought years ago, to use on my rimfire and revolver. It seemed to work pretty well.

LBT sent only one compound for polishing, which was a tad dry, but a squirt or two of KROIL made it good to go again, so I figure why not? Or, I have some JB bore cleaner I could use, if that would be better. What you do, is anoint the bullet with the compound, then roll it between two metal bars to imbed the compound in the jacket metal, then load and shoot.

I am on the edge of what I think I know here, so please, anybody jump in and straighten me out, if I am too far wrong.

I figure, like in the Tubbs Final Finisher kit, a long, jacketed bullet at lower velocity should do just fine.

I would like to use the powder I have on hand, so does anyone have a reduced velocity load for the 257, with jacketed 100 or 117 gr bullets using Unique or Universal Clays? Or would the lowest velocity load in the manuals be O.K., using IMR or H4831, or H4350?

Personally while I've had good luck lapping barrels, I prefer to do it by hand... the thought of a gritty bullet screaming down the barrel at 2500fps gives me the willys LOL

PS: I bought my lapping compound at a local auto parts store. They sell various grits for lapping valves.


-DallanC

DallanC wrote:

... the thought of a gritty bullet screaming down the barrel at 2500fps gives me the willys LOL -DallanC

Yeah, that is giving me second thoughts, too, or it would have been done.

There is an engineering company that sells a kit, and David Tubbs, one of our premier long range competitors, recommends his "Final Finish" kit highly, and the test relults seem positive. (naturally)

It has 75 bullets, 10 each impregnated with 5 graduated finer grits, + 25 for a "tune up"somewhere down the road. I figured that instead of spending $50 for the grit impregnated bullets and a special powder that I would never use again, if the LBT firelapping set worked o. k. for my revolver and 22 rifle, it might work for a big bore.

I guess there are two possibilities: Either it'll work or it won't....

DEFINITELY gotta think about that some more, though.

O.K., I think I got this figured out, at least the part about the jacketed, grit loaded bullet at 2500 fps.

I just got a good price on some 25 Cal cast bullets on da 'Bay. I have some LBT bore lapping compound left in my firelapping kit, which didn't seem to hurt my 22 or 357, sooooo... I am going to try 10 rounds, then do 10 more with JB Compound, which is finer. That should be plenty.

I found a load in my RCBS cast bullet Handbook that uses Unique for around 11-1200 fps., so that takes care of the screamers, although I did find a load in my reloading manuals that went "only" 2300 fps.

Wish me luck !

I wish you luck. I do agree with Dallan that you will get the results you want by lapping by hand and you will probably do a better job. You didn't give us an idea of the age of the rifle or how many rounds down its barrel. If it's a new rifle it takes time for a factory barrel to shoot in before it smooths out. Usually 100 rounds or so. Hand lapping will smooth it cheaper.
If you do shoot the 'grits' be careful not to over do it. Shoot a few, clean and try a few regular loads to check accuracy and see if you still get the copper foulding before shooting more lapping rounds.
I have my fingers crossed for good results!