JohnH
08-14-2007, 04:29 PM
Wasn't going to say anymore on this, but I know quite a few here are shooting SKS's and may find this useful.
I was put off using magnum large pistol primers, as I was getting a peirced primer at a rate of 1-2 per five rounds fired. I began thinking that perhaps the pin was long, but examining the primers with magnifiers it was obvious that the shape of the strike was that of a truncated cone, with the flat of the cone about 1/32 in diameter, with a quite sharp corner at the edge. Every peirced primer was blown out at point. I pulled the firing pin, and did indeed find a sharp corner at the edge of the firing pin nose.
I took a jewelers file and very lightly reshaped the nose of the firing pin to a more rounded shape. 40 rounds later, not a single peirced primer, groups size is a very steady 1 1/2 - 2", same as I was getting from the Remington case with small rifle primers.
The load I'm using is 21 grains of IMR 3031 and the Lee 312-155-2R. From my 16" barrel this load clocks a meek 1390 fps. There was no question in my mind that the problem was something other than pressure related.
Seems the good news is that there is hope for using large primer pocket cases with low pressure loads and good results afterall. Thanks to all who posted on the previous thread
I was put off using magnum large pistol primers, as I was getting a peirced primer at a rate of 1-2 per five rounds fired. I began thinking that perhaps the pin was long, but examining the primers with magnifiers it was obvious that the shape of the strike was that of a truncated cone, with the flat of the cone about 1/32 in diameter, with a quite sharp corner at the edge. Every peirced primer was blown out at point. I pulled the firing pin, and did indeed find a sharp corner at the edge of the firing pin nose.
I took a jewelers file and very lightly reshaped the nose of the firing pin to a more rounded shape. 40 rounds later, not a single peirced primer, groups size is a very steady 1 1/2 - 2", same as I was getting from the Remington case with small rifle primers.
The load I'm using is 21 grains of IMR 3031 and the Lee 312-155-2R. From my 16" barrel this load clocks a meek 1390 fps. There was no question in my mind that the problem was something other than pressure related.
Seems the good news is that there is hope for using large primer pocket cases with low pressure loads and good results afterall. Thanks to all who posted on the previous thread