I recently finished a .260 build. Aero precision upper/lower, 20in krieger barrel, slr adjustable gas block, and aero precision bcg(high pressure). I am getting pressure signs on my case head, even on the low end of my load development. Cases are not beat up, primers are great, no extractor marks. Just a lot of flow around my ejector, not on every case. I would say 50%. I worked from 42-43.5 grains of h4350. I tried 140 class and 130 class bullets. All with similar results. If I close the gas block no pressure signs at all. Even worked up a little higher 43.8. Would a heavy buffer slow my unlock down enough to help with brass flow?
- Thread starter rjbyrd
- Start date
Check case length, may be jamming the mouth into the end of the chamber neck. This can impede bullet release, causing pressure spike.
If not that, I've got nothing; I have no experience with adjustable gas blocks or special bcg's.
Greg
If not that, I've got nothing; I have no experience with adjustable gas blocks or special bcg's.
Greg
When you have the gas turned off there are no pressure signs, is that correct? No issues when extracting the fired round? Just pull the charging handle and it comes right out with no pressure signs???
Correct no pressure signs when gas is off cases extract with ease. As to brass trim length, on the new hornady brass I think used they ranged from 2.025-2.029. After firing I got 2.020-2.031. Max trim length I thought was 2.035 and planned on trimming to 2.030.
Rifle length gas system. Port size I am not to sure about will have to pull the gas block tomorrow and check. Rifle buffer dpms standard weight.
Rifle length gas and buffer. Standard dpms rifle buffer. Have to pull gas block tomorrow to check port size.
Roughly 5.9 oz buffer, you'll want to heavy up buffer. Port size is too big, heavier buffer (7.5-8 oz) is what you'll want. Adjust gas block (starting from "off" / will not cycle or lock back) until will lock back on empty magazine / cycle 100% reliably.
Thank you guys, I will try a heavy buffer. Hopefully it works.
I bought the jp heavy captured silent buffer. It just came today, when I made the swap I thought I would way them. My original came today in at 4oz the jp came in at 6oz. The jp was spring and rod still attached so not very scientific. I expected the jp to be heavier, not knocking it because I have not tried it yet. Has anyone else tried it?
Was the chamber reamed by the builder, and does the actual chamber neck diameter and length conform to SAAMI spec? Does the neck configuration call for neck turning?
43.5gr of H4350 should be near but not be over max in a SAAMI chamber with 140's, but if neck clearance is not ample, you could be seeing symptoms somewhat comparable to what you are reporting.
Ejector flow should only be occurring at peak pressure, not following unlock, but it's not impossible that the unlock is occurring earlier than optimal.
While a match reamer is not a bad idea for a bolt gun, it may not be best for an AR application. Your posts do not appear to cover this area.
The observation about no pressure signs with the gas turned off, but problems with it on falls outside my personal experience
Greg
43.5gr of H4350 should be near but not be over max in a SAAMI chamber with 140's, but if neck clearance is not ample, you could be seeing symptoms somewhat comparable to what you are reporting.
Ejector flow should only be occurring at peak pressure, not following unlock, but it's not impossible that the unlock is occurring earlier than optimal.
While a match reamer is not a bad idea for a bolt gun, it may not be best for an AR application. Your posts do not appear to cover this area.
The observation about no pressure signs with the gas turned off, but problems with it on falls outside my personal experience
Greg
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I honestly don't know if the smith reamed the barrel or any of the specs. The barrel was bought here second hand. It is stamped 260 Rem Baldwin guns works llc and I was told it was a krieger.
