I built a 6.5 CR on Aero receivers using a 20" Proof barrel with a +2" gas system. I've tried it with a rifle length buffer system using the Aero M5 rifle springs as well as a Sprinco Green. It short strokes with both setups. I just put a carbine buffer tube on the rifle and tried a Sprinco White and I'm having the same issue. I know that this barrel has a .086 gas port and I'm thinking that between the port size and the short dwell, I just cant get enough gas to run it. I'm thinking about opening it up to .090 or even .093. Anyone had this issue? What was your solution?
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M5 6.5 CR Shortstroking
- Thread starter owtlaw
- Start date
When you say short stroking, what do you mean? Will it fire a round and not pick up a second? If you aren’t using an adjustable gas block, there is a chance it may be over gassed.
I had the same setup you have using an Aero builder’s kit, 20” proof steel barrel, Toolcraft BCG, and Aero rifle length receiver extension kit and had no problems what so ever. I did have an adjustable gas block and dialed it in. I don’t recall that I ever tried it wide open.
I had the same setup you have using an Aero builder’s kit, 20” proof steel barrel, Toolcraft BCG, and Aero rifle length receiver extension kit and had no problems what so ever. I did have an adjustable gas block and dialed it in. I don’t recall that I ever tried it wide open.
If it's sluggish but works fine with a suppressor, you're likely under gassed. Reducing the weight of the buffer would be the first step. Double check to make sure you can manually lock the bolt to the rear to rule out bolt catch/mag issues. Also double check gas block/gas port alignment.
You swapped out springs but what buffer weights have you tried?
You swapped out springs but what buffer weights have you tried?
Agreed with above statement about undergassed. A lighter buffer can help AND will have less recoil due to less reciprocating mass. I use lots of AP products and 0 issues with any of them. The 1st 6.5creed barrel I bought wad from them (18") and used a non-refundable block. Fired 25 boxes the day I assembled it and ran 100% w/standard weight buffer and spring.
Another thing is if you use a low profile block w/ a straight tube it can cause drag on the key even though it seems aligned. Easy way to check is pull the takedown pins, have upper assembly pointing down about 45°, unlock the bcg, pull back on it 1/2 way and release it. If it goes into battery w/o extra help, then it should be gtg. Or just keep it assembled and retract it with thumb pressure and release and it should go into battery w/ spring pressure.
Try installing some fresh SpringCo Gas Rings in your bolt.
If no improvement with fresh Gas Rings just open up the gas port and use a Adjustable Gas Block.
If no improvement with fresh Gas Rings just open up the gas port and use a Adjustable Gas Block.
Problem solved I think. As embarrassing as it is to report this, I pulled the gas block and actually pin gauged the port. UGH!!!
it was at .071. WTH???? I figure that because it is listed as .086 on the Proof website that it would in fact be at .086. I set it up on my mill and cut it out to .084 as I had that reamer sitting on the cart. I'm betting it will run like a race horse on crack now. Trust but verify.
it was at .071. WTH???? I figure that because it is listed as .086 on the Proof website that it would in fact be at .086. I set it up on my mill and cut it out to .084 as I had that reamer sitting on the cart. I'm betting it will run like a race horse on crack now. Trust but verify.
that's pretty sad as the 4 PR barrels I have (2 260rem, 2 6.5creed) are all overgassed even with +2 on both 22 and 24" barrels.
Issue solved. I think i could have done better if i would have taken it to .078. But it is functional now. I put an Odin works tuneable GB on it. Now im running a Sprinco Red with a 3 oz buffer and it runs smooth.
I had this exact problem with a Criterion barrel (18" rifle-length .308 with a .068 port). Called them and was informed that I was wrong despite having put multiple buffers and springs on trying to get it to function. Opened it up to .093 after another AR manufacturer here PM'd me and told me what was up. It has ran flawlessly since the day I put it up on my drill press.
What a frustrating experience.
Glad you found a fix.
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