Toymaker
02-03-2014, 02:56 PM
I don't think this is a problem, so I'm really looking for comments and opinions.
The rifle is a rolling block in 45-70, 30 inch barrel, 6 grooves, 1:18 twist, 0.457 inch bore diameter. Usually I use a 405 grain, 0.459 inch diameter, hard cast bullet (LaserCast) by Oregon Trail. Lube is whatever they put on them. My Saeco hardness tester says the BHN is 35. The brass is Starline, trimmed to maximum recommended length as necessary. I full length size, expand and let mouth tension hold the bullet. Cases are annealed after 3 uses. Primer is CCI Large Pistol and powder is 23.0 grains of IMR SR 4759. Velocity is right around 1,200 fps. OAL is set so the bullet just engages the rifling.
The "situation" is streaks of lead in the rifling at the bore. I've pushed a tight patch down the bore from the muzzle in increments so I know, within 6 inches, where they are located. Accuracy is less than 1 MOA (3/4 inch at 100 yards) off the bench; under 2 inches at 200 meters. Accuracy is consistent until, as I load a cartridge, I feel the cartridge resist loading before it engages the ejector (more than 10 shots/less than 15). I remove the cartridge and run a tight patch through the bore to remove the lead shavings. If I don't the shot will go high out of the group by about 1 inch at 100 yards.
A black powder load of 70 grains Goex FFg, compressed 0.26 inch, cardboard wad with a bit of newspaper on top, CCI Large Pistol primer, fire formed Starline case will do much the same for accuracy. I wipe between each shot with a wet patch (moose milk) and see lead streaks/shavings and, of course, there's no build up.
Recently I've started experimenting with a 500 grain, 0.459 inch bullet which I cast. BHN is 8.7 and I lube with a bees wax/paraffin/Vaseline/STP oil treatment mix which has proven very good in a .451 Rigby with a 525 grain bullet. Everything is the same as above except I'm trying Accurate 5744. I'm getting the same streaks/shavings of lead in the same location. I haven't experimented enough yet to comment on accuracy. I may need to harden the alloy a little more. However, it appears that 1,200 fps is going to be the magic number again.
As I said, I don't consider it a problem since accuracy is good and stays that way through a competition relay. But I would be interested in comments and opinions. Its the best way to learn. Thanks.
The rifle is a rolling block in 45-70, 30 inch barrel, 6 grooves, 1:18 twist, 0.457 inch bore diameter. Usually I use a 405 grain, 0.459 inch diameter, hard cast bullet (LaserCast) by Oregon Trail. Lube is whatever they put on them. My Saeco hardness tester says the BHN is 35. The brass is Starline, trimmed to maximum recommended length as necessary. I full length size, expand and let mouth tension hold the bullet. Cases are annealed after 3 uses. Primer is CCI Large Pistol and powder is 23.0 grains of IMR SR 4759. Velocity is right around 1,200 fps. OAL is set so the bullet just engages the rifling.
The "situation" is streaks of lead in the rifling at the bore. I've pushed a tight patch down the bore from the muzzle in increments so I know, within 6 inches, where they are located. Accuracy is less than 1 MOA (3/4 inch at 100 yards) off the bench; under 2 inches at 200 meters. Accuracy is consistent until, as I load a cartridge, I feel the cartridge resist loading before it engages the ejector (more than 10 shots/less than 15). I remove the cartridge and run a tight patch through the bore to remove the lead shavings. If I don't the shot will go high out of the group by about 1 inch at 100 yards.
A black powder load of 70 grains Goex FFg, compressed 0.26 inch, cardboard wad with a bit of newspaper on top, CCI Large Pistol primer, fire formed Starline case will do much the same for accuracy. I wipe between each shot with a wet patch (moose milk) and see lead streaks/shavings and, of course, there's no build up.
Recently I've started experimenting with a 500 grain, 0.459 inch bullet which I cast. BHN is 8.7 and I lube with a bees wax/paraffin/Vaseline/STP oil treatment mix which has proven very good in a .451 Rigby with a 525 grain bullet. Everything is the same as above except I'm trying Accurate 5744. I'm getting the same streaks/shavings of lead in the same location. I haven't experimented enough yet to comment on accuracy. I may need to harden the alloy a little more. However, it appears that 1,200 fps is going to be the magic number again.
As I said, I don't consider it a problem since accuracy is good and stays that way through a competition relay. But I would be interested in comments and opinions. Its the best way to learn. Thanks.