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Old October 15, 2011, 07:29 AM   #1
Cuddy78
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Join Date: October 15, 2011
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New Armalite AR-15, short-stroking?

I just recently bought a brand-new Armalite AR-15 from a local gun show. Full length 20" barrel, fixed-stock , but came with a quad-rail, bi-pod and what looks like an aftermarket A-frame front sight assembly (I may be mistaken). I did an initial cleaning after buying it and it looks absolutely new inside, oiled it up and got ready for the range.

When I went to the range I loaded the PMAG MagPul30 in and started shooting. First shot went off well, but when I went for the next shot all I got was a click. Checked the chamber, empty, let go and pulled the trigger: fired another round. To keep it short, the cycle seems to stop at feeding. It will fire and eject well enough but not feeding the next round. When I charge it again, it feeds fine. Changed mags to the standard 20-round steel and same issues. Guys on the range suggested a possible gas issue. I fired a total of maybe 5 or 6 rounds at the range.

Got it home and noticed when I was unloading that my steel mag was having issues letting rounds go from the left side, but the right side was fine. The PMAG had no issues. I bought a new 30-round steel mag to try another magazine for troubleshooting. When I went to clean/check the rifle again, the bolt and internals were bone dry. I know I oiled it the night before, but I guess the fresh metal soaked all the oil.

Next time I get to the range I plan on using all three mags with 1 round loaded to see if the bolt catches on the follower to check for short stroking. I'm hoping it's a friction issue with new parts, not enough oil, and stiff springs (easiest fix, keep shooting!). Someone else mentioned that I'm using (Federal) .223 Rem and the weapon is stamped 5.56 and I might be getting just not enough pressure as I would from a NATO round. The guys at the range suggested checking that my A-frame is lined up properly and that I may not be getting enough gas to the bolt.

Thoughts? Help? Suggestions?
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Old October 15, 2011, 12:06 PM   #2
tahunua001
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I can think of a few possible reasons.
1 is the ammo. were you using factory rounds or were you shooting a bunch of random loose bullets that the guy at the gun show gave you in a ziplock bag?
2. is you may need more lube. too much friction may be preventing your bolt carrier group from retracting far enough to slip behind the new rounds and strip them from the mag. ARs generally require more lube than other gun designs.
3. is your recoil spring. it may be too tough to allow the BCG to retract far enough to strip a new round from the mag.
4. is the mags themselves, though I doubt that 2 separate mag designs would have the same issue. you could try disassembling them and making sure they aren't stuffed with packing grease and dirt. clean and lube them with CLP and load it to the max and empty it a few times and see if the rounds are catching in the mag.

your 2 easiest things to try just involve cleaning and a little more lube. these would all be fairly easy and inexpensive to fix. I wouldn't do all of them at once though because if it does fix the problem and it comes back some time in the future you'll be stuck guessing what was really wrong with it.

and that "someone else" guy is a moron for lack of a better word. federal is owned by ATK which is the company that runs the lake city ammo plant for the USG. almost all american eagle and federal 223 brass comes from lake city and is actually a 5.56 casing. a lot of the bulk federal and american eagle 223 is actually marked XM193(or XM855 respectively) which is military grade ammo that never went through acceptance trials for military use. it is the exact same round that armalites were designed to fire almost 50 years ago. if you flip your ammo over and look at the head stamp you'll most likely see the letters "L" and "C" and a 2 digit number to mark the year that the brass was made. you'll more than likely see anything between 02 and 08 in the same box of bulk ammo.
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Last edited by tahunua001; October 15, 2011 at 12:17 PM.
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Old October 15, 2011, 02:36 PM   #3
jdillon
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My friends AR was doing the same thing when new. Certain ammo would cycle fine but some would not. We checked everything including the mags. Finally spoke to an retired armorer and his comment was just to shoot it more to loosen it up. Guess what..after running a few hundred rounds through it, it now cycles fine.

Try inserting the mags with the bolt retracted to make sure they seat properly and see if it continues to short cycle. Also shoot good quality factory ammo if you don't reload.
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Old October 15, 2011, 03:32 PM   #4
UtopiaTexasG19
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On a new AR set up I would recommend field stripping the whole bolt carrier assembly and use your finger to wet down every part with gun oil, except the firing pin, then reassemble. Be careful that you do not cut yourself while gently smearing the oil on the inside and outside of every part. As others mentioned, try out a better brand of ammo at first until you have some rounds through the gun and parts mesh together smoother. I am fortunate that my recent AR set up will eat up and shoot anything I run through it including the cheap stuff but some AR's need a bit more pressure initially until they "break in".
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Old October 15, 2011, 08:39 PM   #5
Eghad
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http://www.ar15armory.com/forums/AR1...Tec-t5332.html

Quote:
To see if you have a short stroking problem and not a “Failure to Feed” problem, please perform this test first (assuming your bolt catch and magazine is functioning properly). Insert one round into a magazine that you know to be performing well. Insert the magazine into the magazine well, pull the charging handle to the rear, then release the charging to load the round into the chamber. Safely discharge that round. After the round has been fired the bolt should automatically be locked to the rear by the bolt catch and the empty magazine. If the bolt is closed on the empty chamber, then it did not travel far enough to the rear to be held by the bolt catch, and your rifle has short stroked.
Short stroking is a symptom of a problem with the gas system in the rifle. There are 7 parts of the AR gas system. In the upper receiver group, you have the barrel (gas port), front sight base, and gas tube. In the bolt carrier group you have the gas key, the carrier, the bolt, and the gas rings.
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Old October 16, 2011, 07:34 AM   #6
madcratebuilder
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Quote:
I just recently bought a brand-new Armalite AR-15 from a local gun show. Full length 20" barrel, fixed-stock , but came with a quad-rail, bi-pod and what looks like an aftermarket A-frame front sight assembly (I may be mistaken). I did an initial cleaning after buying it and it looks absolutely new inside, oiled it up and got ready for the range.
I really don't think you have a NIB rifle. Parts have been changed out. If someone changed the front sight and did not get the gas port aligned perfect you well have a under gassed rifle. A under gassed rifle well not feed the next round when fired, just as you are experiencing. Very unlikely you have a RE spring or buffer issue. The A1-A2 RE/spring/buffer is pretty fool proof on a 20" gas system.

I would shoot some quality 5.56 ammo and see if the bolt is held back on the last round.

Is this new front sight pinned or clamped?
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Old October 16, 2011, 07:41 AM   #7
Marquezj16
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+1 on Eghad's comment.

If you are not short stroking, then I would go with running it wet (more lube) and trying out out different mag (which you are already doing).

I doubt that a good AR from a good manufacturer like Armalite would require a break in but I could be wrong. But it would not hurt to have good quality ammo, although I used Monarch on mine for the first hundred rounds (yes it was inexpensive).

Hope you get her running.

Safe shooting.
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Old October 16, 2011, 02:53 PM   #8
Cuddy78
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First, thanks everyone for the replies so far. Many of you mentioned using "quality" ammo. What brands should I be looking for and which should I avoid?

@ Tahanua001
Quote:
were you using factory rounds or were you shooting a bunch of random loose bullets that the guy at the gun show gave you in a ziplock bag?
I'm using a brand new box of Federal Ammunition 223 Rem 55gr FMJ I bought at WalMart. It's about the only 223 they had on the shelf at the time. The head stamp just says " F C 223 Rem."

@jdillon
Quote:
after running a few hundred rounds through it, it now cycles fine
Thanks for the info.

@UtopiaTexasG19
Quote:
field stripping the whole bolt carrier assembly and use your finger to wet down every part with gun oil
Thanks, I'll try that.

@Eghad
Quote:
After the round has been fired the bolt should automatically be locked to the rear by the bolt catch and the empty magazine
Thanks for the link. I plan on trying that when I get it out to the range next as part of my troubleshooting-shooting.

@madcratebuilder
Quote:
If someone changed the front sight and did not get the gas port aligned perfect you well have a under gassed rifle
I'm thinking that the most likely answer, but I 'm hoping just oil and break-in will do the trick first. I also doubt it's NIB, but it looked nice at the show. The front sight has two hex/allen screws at the bottom. It's also a "flattop" style removable front sight. Once I figure out how to post pictures on here I'll add a couple. How do I make sure the gas ports are aligned? Just take off the front assembly and eyeball it?

@Marquezj16
Quote:
I doubt that a good AR from a good manufacturer like Armalite would require a break in
I would have thought the same thing, but it might be this after market front sight not being aligned.

Again everyone, thanks for the insight. I'm going to try going over this from the easiest fix to the more involved. I'm confident with just a little love this rifle will be working great soon.
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Old October 17, 2011, 07:22 AM   #9
madcratebuilder
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Quote:
I'm using a brand new box of Federal Ammunition 223 Rem 55gr FMJ I bought at WalMart. It's about the only 223 they had on the shelf at the time. The head stamp just says " F C 223 Rem."
That could be part of the problem. The rifle is designed to use 5.56 nato spec ammo. Fed white box .223 is anemic. Try some Fed brown box 5.56 or AE XM193.
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