I am in the middle of doing load development (my first) for a large frame 6.5 CM AR. I have shot my first set of tests and have ideas of where to go next with respect to refinement. And I am happy with what I am seeing as far as the loads and my process are concerned. But... I am also seeing case head swipes that I am pretty sure are not over pressure signs. While the CHS is more frequent on higher charge weights it can happen on lower charges and even with factory ammo. So I think the gun is over gassed more than anything. I see primer cratering happening at loads near my expected max. I have an adjustable gas block, but it is at it's extreme range and could not adjust it to the point of the bolt failing to eject and load a new round. I am using a relatively normal weight buffer (approx 5oz). I am ordering a heavier buffer (KAK Industries approx 10oz) in an attempt to slow down the bolt and allow gas pressure to drop a bit before it tries to rotate the bolt. I also plan to examine the bolt face to see if there are any burrs there that need to be dressed up. My goal is to just try to not abuse the brass as much and not have to deal with cleaning up small burrs on the case head before reloading. Or at least reduce the occurrence. I know it may never go away. Also, it might slow things down enough that I can actually tweak via the gas block. I suspect it's not far off from being right as it is now as the recoil is not harsh. For those who are curious, this is a 20" barrel, rifle length gas system, superlative arms adjustable gas block, Tubb flat wire spring and DPMS 5oz rifle length buffer.
My question is... Do I need to start from scratch on my lead development once I put in the new buffer and maybe even tweak the gas block adjustment? Or do I just go ahead with where my prior work is pointing me? I am at the point of loading up some loads that are .1 and .2 grains above and below a given weight. I am not tweaking seating depth as I am limited by magazine depth. My current thinking is to go ahead with the next step and see if it preforms close to expected. If not, then start over. As I type this... one thing I can do is load up more ammo than I need for just one test (setup for two tests) and run tests using the current setup, then swap out the new for old buffer, some fouling shots to tweak the gas system and then run the same tests from minutes before using the new setup and see if there is difference before and after.
Thoughts?
My question is... Do I need to start from scratch on my lead development once I put in the new buffer and maybe even tweak the gas block adjustment? Or do I just go ahead with where my prior work is pointing me? I am at the point of loading up some loads that are .1 and .2 grains above and below a given weight. I am not tweaking seating depth as I am limited by magazine depth. My current thinking is to go ahead with the next step and see if it preforms close to expected. If not, then start over. As I type this... one thing I can do is load up more ammo than I need for just one test (setup for two tests) and run tests using the current setup, then swap out the new for old buffer, some fouling shots to tweak the gas system and then run the same tests from minutes before using the new setup and see if there is difference before and after.
Thoughts?
