Veral (and anyone else who wants to pitch in),
I have a stainless Ruger Bisley in .45 Colt that is giving me a fit. It came with a significant barrel constriction just ahead of the forcing cone, and would never shoot as well as I thought it should, and leaded with almost anything I ran through it, even gas-checked bullets. 108 fire-lapping rounds later, ALMOST all of the constriction is removed. I can just BARELY feel it as I push a lead slug down the bore towards the forcing cone. Before, I had to drive it past this point with several licks from a nylon hammer.
Now, the revolver is pretty accurate, giving me several groups 1-1/2" or less at 25 yards. However, it still leads lightly with most of the loads I've tried. The only thing it doesn't lead with is a Lee 300 gr. gas-check RFN (the only GC bullet I have in this caliber). My goal is to have an accurate gun that will not lead, or at least accumulate lead past a certain point. I thought that the barrel might need breaking in or seasoning after the lapping, but I've fired about 60 rounds since lapping with no apparent relief in the leading.
Specifics are: Ruger Bisley 5-1/2" .45, stainless. Chamber throats are 0.4525", forcing cone area at restriction 0.4514-5", muzzle 0.451". The chambers are aligned well with the barrel (checked witha range rod). Bullets I've used are the afore-mentioned Lee, an NEI 270-gr. Keith belonging to a neighbor, and a new LBT 280 WFN that Veral just cut for me. The alloy I'd like to use is wheelweight +1% added tin water quenched, but I've tried mixing 50% pure lead to soften this up, as well as air cooling. Bullets are sized 0.453" and lubed with LBT soft in a Star sizer. The load I'd like to use is 21.5-22 gr. WW296, and a lighter load of Unique/ Universal at 9.0 gr. or so. The load that doesn't lead is the Lee GC, WW quenched, 0.453". Anything else, softer alloy or lighter loads, sized smaller at 0.4525", still leaves a smear of lead visible under a bright light in the muzzle (but not lumps, and it is easily removed).
The puzzling thing to me is that the leading is occuring in the last 3-4" or so of bore, and is mostly in the LEADING edge of the rifling and on the top of the lands, although there is a little in the grooves. In other words, the lead seems to be in the area of the land/ groove juncture that should have the most "grip" on the bullet as the rifling tries to impart the spin. It is almost as if the bullet, once spinning, is stripping the rifling slightly in the direction of the rifling twist.
With all that said, might the very small constriction still present be causing these leading problems? I hate to lap much more, as I feel that I'm just prematurely wearing out my barrel. Would a different powder be less likely to lead? I think I have all the mechanics right on this gun, except for the very minor constriction, and am puzzled by this continued leading. I'd like to use the WFN mould exclusively for both light (~900 fps) and heavy (~1100 fps) loads, since it seems most potentially accurate. Any input would be most welcomed.
BTW- the new WFN mould casts and releases perfectly, just like all my other LBT moulds!
Many thanks! Regan
