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I recently purchased a AA 18" complete upper and a PSA lower.
After assembly took it out for a test, and it would miss feed every other round. Called AA and sent the upper back. They checked it out and ran 30 rounds through it without any issues. The tech that check it out ask me about my lower and ask if I had purchased the mil spec or the carbine lower. Apparently the 6.5 needs the heavy mil spec buffer. I assumed I ordered the mil spec but after inspection and rereading my shipping paperwork the invoice stated it was a " mil spec length" buffer assembly.
I am ordering the heavier buffer today to fix my issues,....... hopefully.
Anybody else heard of this issue before?
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I use H2 carbine buffers with the Grendel if I'm using a carbine barrel with MLGS, to include 18". It runs very well with that set-up.
The carbine buffers are the same length, just different weights. The standard carbine buffer is 2.9oz, and works better with longer gas systems with less dwell time, like a 14.5" MLGS.
NRA Basic, Pistol, Rifle, Shotgun, RSO
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com
Posts: 11
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hoping I get this resolved soon. driving me crazy.........
Posts: 11
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ordered the heavy buffer kit and changed it out. everything is working fine now. one happy Grendel shooter!
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So... If I'm going to running the JP SCS, will I need the spring package and run a heavier spring?
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1075 tech Wrote:So... If I'm going to running the JP SCS, will I need the spring package and run a heavier spring?
I ended up using a lighter spring with 18" MLGS, .076" gas port. Full weight Nitride carrier. Not sure why it worked out that way. I think the SCS comes sprung heavily for Lo-Mass Carriers, just a suspicion now.
NRA Basic, Pistol, Rifle, Shotgun, RSO
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com
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I'm going to be using an AA 16" which I believe is also MLGS. I plan on a PF Nitride carrier and bolt. I'll have to see how she runs with the SCS and make changes as necessary.
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A not so common issue is if the buffer pin is sitting too high it will catch the bolt just enough to keep it from feeding correctly. Make sure the buffer tube is rotated in enough to partially hold the buffer pin. I have seen this a few times with guy I worked with who bought me "problem" non mil-spec lowers.
Hope it helps.
GM2
