Notice that ND shooter is using a very soft alloy, with negligible leading. What he forgot to mention is that the bullet isn't wearing gas checks!
When I made the mold I was a bit edgy about that light an LFN without gas checks giving acceptable accuracy, as best accuracy with 45-70s is normally attained with much heavier bullets. Since gas checks are becoming more and more prohibitively priced, and a few shooters are asking if I can remove the check shank, I'll give a bit of information on the subject.
I can cut a tiny bearing band IN the check shank, leaving a tiny lube groove, which works out well if the check shank is quite long.
If the check shank is fairly short, the two options are to shorten the mold enough so the check shank is gone, and any decent machinist with a milling machine can do it. The trick to not making burrs in the cavities are to fill the cavities with hard lead, clamp the mold in your milling vise, use a flat pin punch to upset the bullets a bit for an absolute tight fit in the mold. (Displaces metal to eliminate the bullet shrinkage. Then, with a new razor sharp end mill, chase around each cavity so all burrs eliminate are thrown outward, but you won't be able to cut out all the way around both cavities. The tight lead bullets minimize any burrs in these areas.
The second option, with works with both long and short check shanks, is to shoot minus checks, which works great with all but the shortest bullets. Best performance will be obtained when using in and out sizers and filling the check shank with bullet lube, then being half carefull not to knock it off when seating the bullets.
I don't believe ND lapped this barrel. If I could twist every bodies arms to make them firelap their guns I would do it and make them all my friends, and especially if they are going to shoot PB bullets.
The best results I've seen with pb bullets, so far as accuracy and power, was with a 444, loaded for tight compression with 296 under a 280 gr WFN, cast of water quenched WW alloy, with LBT lube. The barrel had been lapped until push throughs stayed tight and ran smoothly from breech to muzzle. Velocity was a tad over 2400 fps, accuracy was consistently an inch or less at 100 yards, probably with 5 shot groups, and perhaps only three. I shot the gun, offhand, and it was snappy for sure, with plenty of recoil for healthy strong bodies. I don't reccomend that anyone try duplicating that performance, but am telling of it to let you know that plainbase bullets can perform remarkably well if the barrel, bullet lubricant, and bullet hardness are all top notch.
