bowhunter-tw Report post Posted November 24, 2022 I am loading for a 6mm grendel and getting some very heavy case swipes, it is creating a bur / extractor plunger mark. These loads shouldnt be too high for this cartridge but maybe? Are there other things that could be causing this? Ive got an H1 buffer. Gas timed with suppressor. Any help appreciated 80gr sp 28-28.6 gr tac all loads showed marks 58gr vmax 31-32gr AA2230 all showed marks 32 gr heavy mark and bur Share this post Link to post Share on other sites
Azdiy Report post Posted November 25, 2022 Make sure your overall length is to the book and not too long. If you are crimping, try a couple without a crimp and single feed them by hand to make sure the bullet doesn't move. Maybe also try it without the suppressor. Share this post Link to post Share on other sites
bowhunter-tw Report post Posted November 25, 2022 1 hour ago, Azdiy said: Make sure your overall length is to the book and not too long. If you are crimping, try a couple without a crimp and single feed them by hand to make sure the bullet doesn't move. Maybe also try it without the suppressor. I’ll double check length. These were un crimped. I can try un suppressed but if it wont shoot suppressed its not worth shooting for my intent. It just seems odd not to be able to reach published velocities and already show pressure signs. The primers look a little cratered also. I guess I was wondering if gas timing or buffer weight would affect pressure signs? Share this post Link to post Share on other sites
bowhunter-tw Report post Posted November 25, 2022 Also would a large freebore and bullet jump affect this? The barrel was chambered by an older gun smith and for 105’s for the guy I bought it from Share this post Link to post Share on other sites
Azdiy Report post Posted November 25, 2022 Understood about the suppressor, but it wouldn't hurt to try one or two just to try to isolate the problem. Maybe concentrate on the 80 grain bullets since that chamber is throated for heavier bullets. Check your case length and maybe bump the shoulder back four or five thousandths just to try to get to a baseline. Generally a longer bullet jump has less pressure, that's why the 556 NATO chamber will handle the hotter 556 ammo because it has a longer throat than the wilde chamber or the 223 chamber. I don't know much about buffer weight and gas pressures affecting that. Share this post Link to post Share on other sites
AzDiamondHeat Report post Posted November 25, 2022 It sounds like more of a timing issue or a pin issue. Back in the day there was info floating around about sharp edges on pins causing swipe marks on very tame loads. Check your pin. Maybe try a new pin or bcg to see if it changes. Timing can also cause swipes. You say it is timed but timing changes with each load. Share this post Link to post Share on other sites
L Cazador Report post Posted November 25, 2022 Your 58g. loads are on the maximum side but your 80g. loads are middle of the road. With that long freebore I would think the only thing left is excessive shoulder bump. How much are you bumping shoulder? Share this post Link to post Share on other sites
