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Cycling problem new AR15

3K views 21 replies 7 participants last post by  jwrauch 
#1 ·
Finally got to the range last week and sent 90 perfect rounds down range. The only problem was finding out that the gas block rail was lower than the receiver rail so the iron sights were impossible to adjust correctly (first AR- amatuer mistake).

Today i got the gas block changed out with the proper height rail. Took it to the range to sight it in, but the rifle won't cycle properly.

It loads when charged, fires, ejects, but won't feed. Tried three mags with two different brands of ammo. Same results.

Is this more than likely a gas pressure issue? Clogged tube? Loose tube?

Thanks in advance from an AR newbie.
 
#2 · (Edited)
Finally got to the range last week and sent 90 perfect rounds down range. The only problem was finding out that the gas block rail was lower than the receiver rail so the iron sights were impossible to adjust correctly (first AR- amatuer mistake).
I never understood the reasoning for that....

Today i got the gas block changed out with the proper height rail. Took it to the range to sight it in, but the rifle won't cycle properly.

It loads when charged, fires, ejects, but won't feed. Tried three mags with two different brands of ammo. Same results.

Is this more than likely a gas pressure issue? Clogged tube? Loose tube?

Thanks in advance from an AR newbie.
Well it sounds like the only thing that changed was your gas block. First make sure the tube is connected in there right... if you take it back apart you might as well make sure the tube didn't become crimped or something during install and that it's free of obstruction... but assuming everything is connected right it sounds like it's your gas block... what type did you get?
 
#3 ·
TACAV- I was stunned to learn the standard sights won't work on several flavors of entry level ARs. The AR is an Anderson AM15.

The old block was a low railed block about 1/4" shy of level with the receiver rail. The new one is the same style but has a slightly raised rail. The guy who changed it out is a gunsmith, so I figured he knew what he was doing.

Now that I look at it even closer, the front sight does seem to lay left just a tiny bit.
 
#4 ·
Sounds like the gas port in the barrel may not be properly aligned with the hole in the gas block. I had a similar problem with one of my 1st builds. Just needed to re-align the hole in the barrel with the hole in the block. JR
 
#6 ·
Serious question- I'm pretty good with mechanical doodads and such, but is aligning a block something a complete AR newb can/should do? Gotta ask because I've caused 'problems' just diving into stuff before. Lol!
 
#7 ·
I am no gunsmith and don't have all kinds of fancy tools. I aligned mine by making a mark on the barrel in line with the gas port and a mark on the block that bisected the barrel opening and lining them up. Maybe some of the other guys here can elaborate more. JR
 
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#8 ·
Thanks, JR. I just watched a couple YouTube videos on the subject. Seems fairly straight forward. I may remove the tube and clean it, too.

Looks like owning an AR is like owning a bass boat-- sooner or later, you'll end up knowing how to work on just about every widget, thingamajig and doohickey on it!
 
#10 ·
This is what's happened to me over the last few years.

ARs can do screwy things when you tinker with them sometimes. Sounds like a gas problem as folks previously described (I kinda evolved into figuring out malfunctions after having a problem child AR as well as after on a different one screwing with a heavier buffer spring in anticipation of operating suppressed but not having the can yet--standard weight buffer--An ST-T2 buffer solved all the problems suppressed or not). Also seen a too-high ejector which is a kinda screwy malfunction.

Sounds like there isn't enough pressure to get the bolt back far enough to clear and feed another round (short stroking). Try the gun with one round in the mag and see if the bolt locks back. If not this may well be your problem. Something happened to the gas system (misalignment, bent/blocked tube, etc.).

If it worked well before the feed ramps are probably fine but this is the first thing I check these days.

One thing which might be helpful is to have an observer look at the bolt cycling and where it's throwing its brass (not a be all end all but can give you some ideas).

Kind of late here to the party, but one solution if you can't get your sights to align is buy a quality optic and use the sights on a different build. ACOGs are really nice (and have these on some of my M4s), but (thanks to TAC) I've found the Vortex line with the etched reticles (like the Spitfire or Strike Eagle if you want magnification) to be excellent in this regard (as a stand alone optic) and value priced.
 
#11 · (Edited)
Thanks, TX, TACAV and JR-

Great idea about the one round in the mag. Should have thought about that myself.

I hope to shoot again tomorrow with a buddy who's a fine shade tree gunsmith. We'll run her through the gauntlet.

BTW- JR? That AR15 site is dangerous. I gotta get up early but all I want to do is keep reading. Lol!
 
#14 ·
Sweet bat snot on a Krispy Kreme crueller!

Thought to thoroughly clean the AR before doing any adjustments. Googled cleaning BCG and followed the videos.

Laws! Not even 110 rounds through this thing and the innards are Walking Dead zombie-like nasty. It would take 500 rounds in the XDsc to get this bad.

Is this normal? Maybe I greased her up too much after cleaning/lubing for the break in?
 
#15 ·
Sweet bat snot on a Krispy Kreme crueller!

Thought to thoroughly clean the AR before doing any adjustments. Googled cleaning BCG and followed the videos.

Laws! Not even 110 rounds through this thing and the innards are Walking Dead zombie-like nasty. It would take 500 rounds in the XDsc to get this bad.

Is this normal? Maybe I greased her up too much after cleaning/lubing for the break in?
Depends on the ammo used. You don't need to soak a BCG contrary to popular myth. There is a raised ring of metal mid-way around the bolt where it contacts the inside of the carrier as it locks/unlocks. There are 4 small rails on the upper and lower edges of the carrier on both sides where it contacts the inside of the upper receiver. A bit a grease or oil along those parts are all it needs for most cases since the rest of the surface doesn't even contact the receiver - thus lube there only serves to attract gunk. Use pipe cleaners to clean inside the gas key at the top of the carrier and make sure your gas rings are staggered. o_O

Product Red White Technology Line
 
#16 ·
You didn't put any oil in the gas tube, I hope?
 
#19 ·
One reason my time there was very brief. I check in maybe once every couple years. No change.
I get better info here. Less pretense and bravado.
 
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#20 ·
Duly noted, gents. I might lurk and graze the threads, but I've already read some pretty snarky stuff.

There's a lot of solid info there that took some of those members quite some time to write, but the general tone is a little too armchair for this ol' mountain boy.

What you kind folks have provided has been invaluable. Thanks to everybody.
 
#22 ·
My thoughts exactly. It's been about 6 months since I've been back. Actually what finished me from going there a lot was a similar problem to this thread. One of the "enlightened " told me to replace my POS gas block with a high $$ one. I asked him if he ever had to do anything on a budget and you would have thought I had insulted his mother !!!! JR
 
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