Posts: 10
Threads: 1
Joined: Mar 2020
04-12-2020, 01:58 AM
(This post was last modified: 04-12-2020, 02:10 AM by Lee Marlin.)
Hello, I have a problem I can't seam to figure out. I built an AR with a palmetto arms upper in 6.5 Grendel. It has a mid length gas tube and a 20 bbl. I had an adjustable gas block but I replaced it with a standard one. My problem is Factory ammo ( Hornady american 123 BTHP ) cycles fine. But when I make hand loads it will not cycle. I have even went over book max with several powders, AR COMP, H322, and H335.
Everything I've read says it should cycle with a standard buffer. Any suggestions would be helpful. Has anyone else had this problem?
Thank you in advance.
Posts: 206
Threads: 12
Joined: Jul 2017
Define exactly what issues you're running into with cycling. Mid gas on a 20 inch barrel is unusual all by itself.
Posts: 10
Threads: 1
Joined: Mar 2020
Bolt will not cycle a second round. It kicks the first out just fine. All factory ammo works fine.
Posts: 6,193
Threads: 170
Joined: Mar 2015
Lee Marlin Wrote:Hello, I have a problem I can't seam to figure out. I built an AR with a palmetto arms upper in 6.5 Grendel. It has a mid length gas tube and a 20 bbl. I had an adjustable gas block but I replaced it with a standard one. My problem is Factory ammo ( Hornady american 140 BTHP ) cycles fine. But when I make hand loads it will not cycle. I have even went over book max with several powders, AR COMP, H322, and H335.
Everything I've read says it should cycle with a standard buffer. Any suggestions would be helpful. Has anyone else had this problem?
Thank you in advance.
Is this a creedmoor? To the best of my knowledge there is no 140 grain factory grendel ammo.
Posts: 10
Threads: 1
Joined: Mar 2020
OOps my bad 123's. It's a Grendel.
Posts: 6,193
Threads: 170
Joined: Mar 2015
Check that the gas block is over the gas port.
What was the max charges used for those powders?
Posts: 10
Threads: 1
Joined: Mar 2020
A5BLASTER Wrote:Check that the gas block is over the gas port.
What was the max charges used for those powders?
I have checked the Gas block. AR COMP 28gr, H322 27.6gr, and H335 30.5gr.
Posts: 6,193
Threads: 170
Joined: Mar 2015
Lee Marlin Wrote:I have checked the Gas block. AR COMP 28gr, H322 27.6gr, and H335 30.5gr.
Does the action lock back properly on last round and empty mag?
How many rounds have you fired? Is the gun broke in yet?
Posts: 10
Threads: 1
Joined: Mar 2020
A5BLASTER Wrote:Does the action lock back properly on last round and empty mag?
How many rounds have you fired? Is the gun broke in yet?
It does not lock back on the last round or empty mag. I have shot 250 rounds. Only my hand loads will not lock back factory works great.
Posts: 989
Threads: 64
Joined: Feb 2019
Lee, if factory ammo is working fine and your reloads don't it might be time to evaluate all the steps in your reloading process.
How the fired brass looks indicates how rough or smooth the chamber is. Does yours look normal?
Is your sizing die setup correct? Best of luck on finding a solution!
Posts: 6,193
Threads: 170
Joined: Mar 2015
Lee Marlin Wrote:It does not lock back on the last round or empty mag. I have shot 250 rounds. Only my hand loads will not lock back factory works great.
What buffer and spring do you have in it?
Posts: 10
Threads: 1
Joined: Mar 2020
A5BLASTER Wrote:What buffer and spring do you have in it?
Whatever is standard for a 5.56 mil spec tube. I'm new at this so I'm not sure of the weight of the spring or the buffer.
Posts: 1,397
Threads: 48
Joined: Jun 2019
I know you checked the gas block already, but to me it sounds like a rifle isnt getting enough gas.
Posts: 6,193
Threads: 170
Joined: Mar 2015
Lee Marlin Wrote:Whatever is standard for a 5.56 mil spec tube. I'm new at this so I'm not sure of the weight of the spring or the buffer.
There is 2 mil spec tubes.
Does it have a adjustable stock are a fixed stock?
It really sounds like you have a gas issue. If you still have the adjustable gas block put it back on and see if you can adjust the gas to run with your handloads.
Sounds like your handloads are over gassing the rifle possible.
Posts: 6,193
Threads: 170
Joined: Mar 2015
Also if you can grab us a few pics of the gas block that's installed now and the gas tube before you remove it from the barrel.
We might beable to spot the problem.
Posts: 10
Threads: 1
Joined: Mar 2020
A5BLASTER Wrote:There is 2 mil spec tubes.
Does it have a adjustable stock are a fixed stock?
It really sounds like you have a gas issue. If you still have the adjustable gas block put it back on and see if you can adjust the gas to run with your handloads.
Sounds like your handloads are over gassing the rifle possible.
I have an adjustable stock. I have the adjustable gas block. I need to do some more loading. Unfortunately the range is closed until May 4. But I will try the the other gas block. I did not think that to much gas would be a problem. Thanks for the help.
Posts: 6,193
Threads: 170
Joined: Mar 2015
Lee Marlin Wrote:I have an adjustable stock. I have the adjustable gas block. I need to do some more loading. Unfortunately the range is closed until May 4. But I will try the the other gas block. I did not think that to much gas would be a problem. Thanks for the help.
Overgassed and undergassed can have the same issues at times.
Posts: 1,105
Threads: 8
Joined: Nov 2017
Had the same problem with my 20" PSA upper all I had to do was turn up the adjustable gas block to solve the problem . One thing mine has a rifle length gas tube .
Posts: 30
Threads: 0
Joined: Jun 2019
If factory ammo runs and reloads don't, then the answer is fix your how you're reloading. I size back to factory dimensions in ammo that feeds more than one gun, and have never had any problems. A good case gauge helps.
Posts: 4,287
Threads: 156
Joined: Jan 2017
Having an adjustable stock sounds like it is actually a carbine stock -- which is ok but if so, then it means you have a carbine length buffer tube, and you need to have the carbine spring and a carbine buffer weight as well. If you say "whatever is standard for a mil-spec 556 tube" this also sounds to me like it is carbine length (the carbine system has both mil spec and commercial spec buffer tubes), so verify which type of stock length you have. Could be you have mistakenly put in a rifle spring, maybe a rifle buffer weight also...
So. If it indeed is carbine length stock then which spring exactly is in there and which weight of carbine buffer do you have, perhaps you can go to a lighter weight buffer (really shouldn't need this since factory ammo cycles...)... admittedly I am not a buffer weight expert.
Now as an extra thought, a "mid-length" gas system should be giving lots and lots of pressure and dwell time (maybe even too much dwell but again, not an expert there)... since most 20" barrels are rifle length. Perhaps double check that also.
"Down the floor, out the door, Go Brandon Go!!!!!"
