Posts: 25
Threads: 5
Joined: Nov 2017
So i finally had my Grendel out to shoot for the first time and put about 40 rounds through it.
It will not cycle fully.
It will extract the spent round but will not load a fresh round for some reason.
Now im no AR expert at all. Bought my first AR last fall and then built this Grendel and never fired it till today.
From what i can figure out it is under gassed or over buffered.
20in McGowen barrel with rifle length gas system.
Adjustable gas block the is tight, aligned. Tried 1/2 turn at a time from closed to full open.
Brownells BCG.
Magpull fixed rifle length stock and tube(A2)
Rifle buffer and spring.
ELander 17? round mags
Shooting Hornaday 123gr ELD
Any suggestions on what to look for?
Thanks
Posts: 682
Threads: 56
Joined: Dec 2016
People sleep peaceably in their beds at night only because rough men stand ready to do violence on their behalf. ― George Orwell
Posts: 6,206
Threads: 50
Joined: Mar 2011
Are you sure the gas block is centered over the gas port? Look for carbon residue on the bolt carrier around the carrier key, you might be loosing gas pressure. If you load one round into the mag and keep an empty mag in the well does the bolt lock back with the bolt catch after you fire the chambered round?
Sounds like the bolt carrier might not be going far enough to the rear to pickup the top round in the mag. If you take the gas block off you might measure the gas port. It is not unheard of for the manufacturer to not have the proper size port.
Posts: 25
Threads: 5
Joined: Nov 2017
Im pretty sure the gas block is aligned properly. I did use one of them little plastic pins made for aligning them.
I have taken off the hand guard and i can not see any signs of a leak, there is also no sign at the gas key of a leak.
The bolt will not lock back when the last round is fired.
Now that i think of it a little more and i cant remember for sure but i think it is cocked also. I fire a round and BANG, hear casing hit cement floor. aim and squeeze trigger, click no boom.
Pull charge handle back and let go, Round chambered.
I do have a Rock River two stage trigger also.
Posts: 185
Threads: 2
Joined: Dec 2017
Can you manually lock your BCG back?
How much free play do you have between bolt and bolt catch?
I recently had a short buffer tube/long buffer combo that couldn't move rearward enough to lock back and couldn't be trusted to strip a round.
Changed out the freak long buffer with a shorter one.
Problem solved.
"The best we can hope for concerning the people at large is that they be properly armed."
-- Alexander Hamilton, The Federalist Papers at 184-188
Posts: 25
Threads: 5
Joined: Nov 2017
It will lock back if i manually pull it back with a empty mag.
Posts: 2,062
Threads: 88
Joined: May 2016
The gas port in my 26" McGowen 6mm Grendel (R+2) could certainly be larger. Still fighting issues after I thought it was worked out with a low mass carrier and a low mass buffer. This thread has some ideas on lightening your buffer and shortening your spring.
http://www.65grendel.com/forum/showthrea...er-Springs
Also, how did you align your gas block? When I put mine together, I set the Superlative block 0.025" off the shoulder per Superlative instructions. That was the first thing I checked when it wouldn't cycle. I took the block off and measured and it should be against the shoulder.
Let's go Brandon!
Posts: 25
Threads: 5
Joined: Nov 2017
Yes mine is against the shoulder as that is where the little alignment pin set it.
I also thought the gas port looked a little small but not knowing anything about what size it should be i figured they knew what it should be.
Posts: 990
Threads: 14
Joined: Sep 2014
Check your gas port. Should be .0945 on a 20” with rifle gas.
Member since 2011, data lost in last hack attack
Posts: 25
Threads: 5
Joined: Nov 2017
I just measured my gas port. It measures .083
Posts: 1,918
Threads: 79
Joined: Oct 2016
ricsmall Wrote:Check your gas port. Should be .0945 on a 20” with rifle gas.
A 3/32 drill bit should have a tiny amount of play, for those of us without an internal micro. (Use a new bit - $1.79 at Lowes)
Nothing kills the incentive of men faster than a healthy sense of entitlement. Nothing kills entitlement faster than a healthy sense of achievement.
Posts: 1,918
Threads: 79
Joined: Oct 2016
SpairParts Wrote:I just measured my gas port. It measures .083
Yep, Lowes it is. Grab the 3/32 and drill it out. =.09375
High-five.
https://www.youtube.com/watch?v=i-zm5pyWPSc
Nothing kills the incentive of men faster than a healthy sense of entitlement. Nothing kills entitlement faster than a healthy sense of achievement.
Posts: 25
Threads: 5
Joined: Nov 2017
Posts: 25
Threads: 5
Joined: Nov 2017
Ok up sized the hole and she now cycles perfect!
Thanks guys much appreciated
Posts: 6,206
Threads: 50
Joined: Mar 2011
Thanks for the update SpairParts, glad you got it sorted out.
