10-23-2024, 12:28 AM
+1 on the neck flattenings, the soft side of velcro not the hooks.
The ejector marks and burrs, well, seems to indicate over-pressure but could also be unlocking late/early (not an expert here).
My own theory on the grendel and 6 Arc is you don't have a large amount of powder - smaller case volume to barrel volume so you may reach 100% burn, you'll still get some more gas expansion but it starts to be diminishing returns, sort of thing. Lever reaches 100% burn at about 16" of barrel.
On the SA gas blocks, they operate 2 ways, full closed to open as a traditional adjustable gas block gradually opening up gas flow, then beyond that they start to bleed off the gas forward of the GB, which is what 300Blk was talking about - good for suppressor ops. I have mine right now on traditional adjustment, what you want to start with is fully open which is not "all-the-way-out".
To the bullets. Which 105 berger, there are a few? tangent or secant or modified (hybrid) ogive? what seating depth are you using (how far off the lands)? what depth do they touch your lands? Using a crimp to prevent bullet sliding forward on the bcg slam?
I have some 105's, they are vld-h, and some 105 Hornady's, running them at 29.7 in my bolt gun (22), and from what I see they would extrapolate to the 24" around 2780, under 52 ksi, so wouldn't expect those burrs/ejector marks like on your brass.
O yes, one other thing, did you do a set of laddered charges, the case volume for the alpha brass is probably different than either Hornady or starline, so you need to do this to know how the powder, lot# and bullet/case react to increases in powder, to see it you're going over pressure. I don't personally think so but to know is better than to assume (my loads are with hornady brass).
From the web... accurateshooter forums, same issue but 22" criterion with +2. he tried all the buffer weights and finally enlarged the gas port to give more gas. Could be food for thought. You can follow the thread here:
https://forum.accurateshooter.com/thread...g.4126202/
The ejector marks and burrs, well, seems to indicate over-pressure but could also be unlocking late/early (not an expert here).
My own theory on the grendel and 6 Arc is you don't have a large amount of powder - smaller case volume to barrel volume so you may reach 100% burn, you'll still get some more gas expansion but it starts to be diminishing returns, sort of thing. Lever reaches 100% burn at about 16" of barrel.
On the SA gas blocks, they operate 2 ways, full closed to open as a traditional adjustable gas block gradually opening up gas flow, then beyond that they start to bleed off the gas forward of the GB, which is what 300Blk was talking about - good for suppressor ops. I have mine right now on traditional adjustment, what you want to start with is fully open which is not "all-the-way-out".
To the bullets. Which 105 berger, there are a few? tangent or secant or modified (hybrid) ogive? what seating depth are you using (how far off the lands)? what depth do they touch your lands? Using a crimp to prevent bullet sliding forward on the bcg slam?
I have some 105's, they are vld-h, and some 105 Hornady's, running them at 29.7 in my bolt gun (22), and from what I see they would extrapolate to the 24" around 2780, under 52 ksi, so wouldn't expect those burrs/ejector marks like on your brass.
O yes, one other thing, did you do a set of laddered charges, the case volume for the alpha brass is probably different than either Hornady or starline, so you need to do this to know how the powder, lot# and bullet/case react to increases in powder, to see it you're going over pressure. I don't personally think so but to know is better than to assume (my loads are with hornady brass).
From the web... accurateshooter forums, same issue but 22" criterion with +2. he tried all the buffer weights and finally enlarged the gas port to give more gas. Could be food for thought. You can follow the thread here:
https://forum.accurateshooter.com/thread...g.4126202/