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high lost rate forming 6mm ppc from 7.62 x 39
dtknowles
Member Posts: 810 ✭✭✭✭
In case anyone doesn't know Lapua .220 Russian and Norma 6mm PPC brass are expensive and not every shop has some. I decided to form some from 7.62 x 39 brass I have. Actually I have been saving Remington brass that uses small pistol primers for this for a while. They are range piok up brass. I bought a used benchrest rifle in 6mm PPC last spring and it came with around 75 cases all preped and probably more than once fired. I am still using those cases after maybe around 3 or 4 reloads without any failing but I know that they won't last forever.
Getting ready to work on my Rem brass I use some less precious FC Large Primer brass. Set out to make 5 but lost a few during die forming and one neck tore during turning but I did get 4 good cases and with them I could shoot 4 shot groups as good as the 5 shot groups I am getting with the other brass, less than 0.40 inches.
Seeing how 6mm PPC is susposed to have small pistol primers I now started make 6mm from my supply of Rem 7.62 x 39 brass. At first this was looking good. I learned form the FC die forming that if sized in two steps with annealing between steps I would not crunch any brass during die forming. Being range brass it could be from more than one lot and it seems that is the case as my first rack of 50 most of the case formed ok but the second rack none would form without crunching, I should not say none because after crunching between half and a dozen I move on, can't waste good brass. Moving on to a third rack of 50 (I had some 250 to 300 pieces of this brass)I had somemore success but only sort of, mostly they did not crunch but I did get some wrinkles and distortions. So, at that point I had almost 100 formed cases but only about half I real nice. I trimmed all the cases to length but only the really nice ones needed trimming because the others were mostly short. I then turned the necks on the nice ones. The next step is to fire form them. I put 6.5 gr. of 231 in the cases and filled them with ground corn cob topped with bullet lube. Only 12 of the first twenty survived this activity. The other eight had large split along the length of the body, actually only 6 one had a small crack that I detected before I fired it and one had only a small crack after I fired it but 6 split wide open, would hate to have that happen with a full charge and bullet. I finished fireforming the rest of the nice cases yesterday with on about one in 5 failing and those had the big split. The first 12 are loaded with 25 grains of Reloader 10X and 60 gr. Bruno Flat based OO bench rest bullets. Might get to the range tomorrow if it does not rain. It pained me to scrap so much brass.
Tim
Getting ready to work on my Rem brass I use some less precious FC Large Primer brass. Set out to make 5 but lost a few during die forming and one neck tore during turning but I did get 4 good cases and with them I could shoot 4 shot groups as good as the 5 shot groups I am getting with the other brass, less than 0.40 inches.
Seeing how 6mm PPC is susposed to have small pistol primers I now started make 6mm from my supply of Rem 7.62 x 39 brass. At first this was looking good. I learned form the FC die forming that if sized in two steps with annealing between steps I would not crunch any brass during die forming. Being range brass it could be from more than one lot and it seems that is the case as my first rack of 50 most of the case formed ok but the second rack none would form without crunching, I should not say none because after crunching between half and a dozen I move on, can't waste good brass. Moving on to a third rack of 50 (I had some 250 to 300 pieces of this brass)I had somemore success but only sort of, mostly they did not crunch but I did get some wrinkles and distortions. So, at that point I had almost 100 formed cases but only about half I real nice. I trimmed all the cases to length but only the really nice ones needed trimming because the others were mostly short. I then turned the necks on the nice ones. The next step is to fire form them. I put 6.5 gr. of 231 in the cases and filled them with ground corn cob topped with bullet lube. Only 12 of the first twenty survived this activity. The other eight had large split along the length of the body, actually only 6 one had a small crack that I detected before I fired it and one had only a small crack after I fired it but 6 split wide open, would hate to have that happen with a full charge and bullet. I finished fireforming the rest of the nice cases yesterday with on about one in 5 failing and those had the big split. The first 12 are loaded with 25 grains of Reloader 10X and 60 gr. Bruno Flat based OO bench rest bullets. Might get to the range tomorrow if it does not rain. It pained me to scrap so much brass.
Tim
Comments
Uh, shouldn't we use small RIFLE primers?
Yes, I meant small rifle primers.
5mm
I have a body die for forming, no decapping stem or anything like that. Without annealing more than 50 percent crunch up like an accordian with you get to pushing the shoulder back. I switched to sizing just the neck first than annealing, this helped but some batches just will not form either way. When I pick up the brass I sort of segregated it by date.
I thought about loading the formed brass and shooting it with real bullets but that would take range time. Fire forming with filler, I can do in my shop. When I did and got a bunch that split lenght wise between the shoulder and the head, I am glad I did it the way I did. I think getting a split like that with a normal load would be a bigger problem. Have you ever had a split like that?
I shot the first 12 cases today with my standard load. The first two were part of my fouling and warm up group, these two cases were a little more than a grain heavier than the mean so I kept them separate. I fired four 5 shot groups alternating 6mm PPC Norma brass and RP 7.62 brass. The RP groups were actually better at 0.40" and a 0.28" at 100 yards. I shot a 0.34" and 0.60" with the Norma brass but I think I pulled one shot on the 0.60" group, pulled is not quite right, the scope hit the bill of my cap during recoil. That was the first real group and as soon as it happened I turned my cap around. I don't know why it happened when it did but I must have done something different because it did not happen with the fouling/sighters/warmup. The three shots for warmup (first shots from a just cleaned barrel)formed a group that measured 0.26" even though it was two pieces of RP brass and one piece of Norma and these rounds are chosen becasue they are out of spec, either neck tension is off or the case weight is different or the bullets have scratches or some other defect.
Tim