Ritchs Precision Guns

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#3266035 - 01/13/21 09:18 PM At won't cycle
JPH sand hills Offline
Seasoned Member

Registered: 02/14/10
Posts: 162
Loc: nebr
Friend called today said his ar will not cycle all the time and action stays closed on last round fired. Has fired factory ammo and reloads. I feel it is the gas block . Any thoughts. Thanks

#3266038 - 01/13/21 09:26 PM Re: At won't cycle [Re: JPH sand hills]
AdamT Online
Die Hard Member III

Registered: 01/04/15
Posts: 2691
Loc: Southwest Virginia, USA
Definitely sounds like low gas pressure. Start with a good cleaning and go from there. Looks for heavy fouling around the gas block area for signs of leakage. Also if experiencing issues, I’d use known quality ammo for testing.
Rich man rolls the dice, Poor man pays the price!

#3266040 - 01/13/21 09:31 PM Re: At won't cycle [Re: JPH sand hills]
crapshoot Offline
Retired PM Staff

Registered: 03/22/02
Posts: 22526
Loc: Henderson,Nevada,USA
Check gas rings also.
I carry a gun because a cop is to heavy.

Average response time for a 911 call is 10 min.
Average response time for a .45acp is 900FPS.

Remember, if you're not pissing off a liberal......You are one!
Ted Nugent

#3266041 - 01/13/21 09:38 PM Re: At won't cycle [Re: JPH sand hills]
GLShooter Offline
PM Sponsor

Registered: 01/09/05
Posts: 5147
Loc: AZ
First thing to do is to make sure the port and block are lined up. Then look at the key and block for leakage. If this is a new build it may need some gas port adjustment.


#3266048 - 01/13/21 11:11 PM Re: At won't cycle [Re: JPH sand hills]
JPH sand hills Offline
Seasoned Member

Registered: 02/14/10
Posts: 162
Loc: nebr
Thank you men for your answers we will start tomorrow.

#3266067 - 01/14/21 03:27 AM Re: At won't cycle [Re: JPH sand hills]
Zastava223rem Offline
Seasoned Member

Registered: 10/19/14
Posts: 320
Loc: Pennsylvania
Build or factory rifle?
If possible, component list?
Low profile gas block or A2 post?
Gas system length?
What specific factory ammo and what was the powder he was loading with?
It sound like its not getting enough pressure in the gas system to completely cycle but if its only on the last round, the magazine could have something to do with it too. Ive seen mags cause so much drag that the reduce bolt velocity dramatically on the last round fired.
A Good cleaning and inspection of the bolt and carrier would be a start.

As stated, the gas block has to be in perfect or near perfect alignment with the port in the barrel, if it is not aligned, you will probably see a lot of soot and carbon around the block where it bled off. The block could also be too far forward or too far rearward causing misalignment.

I ran into a inconsistent cycling issue with my 18" rifle length SPR barrel. Turns out that when I installed the gas block, I ASSUMED that it was machined to have the gas block butted up with the barrel journal since that barrel likely would have a free float handguard. This wasnt the case. I had to have a fingernails thickness between the gas block and the shoulder of the journal to account for a handguard cap with the gas block and it has run everything since.

Edited by Zastava223rem (01/14/21 03:30 AM)
Varmint Rifle Stable
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-Mini Mauser Douglas 26" .223 Rem Leupold VX3i 6.5-20x50
-Sako A7 Coyote .223 Rem Leupold/VX3i 3.5-10x50 CDS

#3266193 - 01/14/21 07:26 PM Re: At won't cycle [Re: Zastava223rem]
mulespurs Offline
Seasoned Member

Registered: 01/04/10
Posts: 132
Loc: NW IA
Oil the action some and see what that does.

Neighbor brought me a new ar that wouldn't run, oiled the bolt carrier and the gas rings thru the holes in the bolt, it runs now.

Saw an article once and the guy oiled his ar with the cars dipstick, just oiled the holes in the bolt carrier so it would run.

They do like to run a little wet in my experience.


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