AR2208
Posted: Tue Mar 22, 2011 7:45 am
Having shot 1K recently with my 308 LG, i noticed that the pressures were way up and the group had opened up considerably since going to a new batch of 2208. Previous testing has shown that the original powder batch allowed me to go to 45.5 grains with a 175 grain projectile, but the new batch would only allow me to get to 43.5 grains before ejector marks were present. The original working load of 44 grains that i used at that 1K match destroyed half of the cases used and loosened the pockets on the remainder. Returning to the original batch has since shown that it can still maintain lower pressures and better grouping at 500 meters.
There is definitely something different about this newer batch. #4845. For years i have just changed new for old lots as required and never had an issue. This is the first time i have been caught out with this powder and luckily it was with a case as strong as the Lapua 308.
I tested at long range at a mates place this weekend just gone to confirm what was going on and once again the new lot showed high pressure and poor grouping at all levels where inconsistent vertical shots were the trend. Win 748 and Re15 showed far better groups all around with more speed and lower pressures. The 2206H was too slow with the velocity to be any good for 1K but did seem to group OK.
Just to see what it would shoot like in my 6BR, i used the same 2208 powder charge as always and with known good bullets and primers and then shot four groups at 500 meters. The smallest was three inches, the largest was 6 inches and this was in good early morning conditions. The previous 1K match, Jeff H had used this rifle, same bullets and old powder batch to shoot a 5 and 7 inch group at a 1000 yards. I think that tells the story.
There is definitely something different about this newer batch. #4845. For years i have just changed new for old lots as required and never had an issue. This is the first time i have been caught out with this powder and luckily it was with a case as strong as the Lapua 308.
I tested at long range at a mates place this weekend just gone to confirm what was going on and once again the new lot showed high pressure and poor grouping at all levels where inconsistent vertical shots were the trend. Win 748 and Re15 showed far better groups all around with more speed and lower pressures. The 2206H was too slow with the velocity to be any good for 1K but did seem to group OK.
Just to see what it would shoot like in my 6BR, i used the same 2208 powder charge as always and with known good bullets and primers and then shot four groups at 500 meters. The smallest was three inches, the largest was 6 inches and this was in good early morning conditions. The previous 1K match, Jeff H had used this rifle, same bullets and old powder batch to shoot a 5 and 7 inch group at a 1000 yards. I think that tells the story.