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Posted: 3/9/2006 1:54:42 PM EDT
[Last Edit: 3/9/2006 1:56:43 PM EDT by -RotorDemon-]
Don't know what the hell is going on with this thing.. I try to insert any of my 26 mags and they won't lock unless the carrier is pulled as far back as possible, drop the charging handle and it loads as normal, Fire, ejects the case, and the carrier gets hung up, pull the charging handle back and let it fly, Loads, fires.. Continued.

I'm no AR guru but I think the carrier is blocking the mag from seating in the mag well, I see no abnormal wear on the carrier/bolt. This first started happening at the January ARFcom Oregon Shoot and it was so retarded I just put it away in embarrassment. I stripped it there, tore it down, made sure everything was in the appropriate place / position, re-assembled and same ol crap.

I think I narrowed it down to the carrier. But I don't want to put a bazillion dollars down just to prove myself wrong, Since the original bolt/carrier has around 1500 rounds through it and was cleaned after every shoot. When the rifle was working properly, it ran every mag flawlessly. AFAIK the mag catch is working properly. with the upper off of the rifle, or even the carrier locked back, they insert, lock and drop free as they should.

The wierd thing about it is when I cycle it slowly it almost seems like the carrier is dragging on the top of the mag, but yet there is no wear on the top of the mag.

When it fails to feed the following round the round is pushed into the feed ramp but then the carrier moves over the top of the round.

Yes it's filthy, I just shot it bolt action style that day.


Upper is a Bushmaster A2
Lower is a DPMS.

Anyone have this problem before?
-RD
Link Posted: 3/9/2006 2:15:01 PM EDT
www.ar15.com/forums/forum.html?b=3&f=66

see if this link will help you at all
Link Posted: 3/9/2006 2:15:25 PM EDT
Pull the carrier out. Does the bolt rotate and move back and forth smoothly in the carrier?
Check the gas tube-does it appear bent or clogged at the breech end?
Is the gas key on tight?
Any chance that the mags were overloaded by one round (31 rounds in)?


Link Posted: 3/9/2006 2:18:01 PM EDT
[Last Edit: 3/9/2006 2:25:51 PM EDT by -RotorDemon-]

Originally Posted By usagold:
www.ar15.com/forums/forum.html?b=3&f=66

see if this link will help you at all



Thanks.. perhaps I a mod can get this thread moved over there.
Link Posted: 3/9/2006 2:20:37 PM EDT
[Last Edit: 3/9/2006 2:25:03 PM EDT by -RotorDemon-]

Originally Posted By Poodleshooter:
Pull the carrier out. Does the bolt rotate and move back and forth smoothly in the carrier?
Check the gas tube-does it appear bent or clogged at the breech end?
Is the gas key on tight?
Any chance that the mags were overloaded by one round (31 rounds in)?





1. Yes
2. No. I used a long pipe cleaner and (dont hurt me) alcohol based non-clorinated brake cleaner to flush the gas tube.
3. Yes
4. All had 30 rounds. I even loaded them with 15. It will do this all throughout the whole mag.

Edit: if I manually cycle it slowly with a loaded mag I end up with the picture posted above. the bolt will start to feed the round and it will slip off and get jammed on the carrier. The bolt has no abnormal slop that would hurt anything.
Link Posted: 3/9/2006 3:01:52 PM EDT
[Last Edit: 3/9/2006 3:02:23 PM EDT by eodinert]
With an empty magazine, is there any interference between the bolt and the mag body? It may be more clear if you remove the follower to check. Cycle the action using the charging handle.

What type of magazines are you using?

With the bolt removed from the carrier, and the upper receiver removed from the lower, does the carrier slide freely in the upper, all the way forward?



Link Posted: 3/9/2006 3:12:53 PM EDT
My initial thought is to check and make sure the magazines are seated properly. There could be dirt on the magazine latch or perhaps it’s broken.
Link Posted: 3/9/2006 3:19:06 PM EDT
so it was working fine before for about 1500rds. Then this came out of nowhere? No new parts were installed before the problem arise?
Link Posted: 3/9/2006 3:47:35 PM EDT
From the picture it looks like the bolt is actually riding OVER the mag, causing a partial feed. What type of mags are you using?
Link Posted: 3/9/2006 3:52:34 PM EDT
[Last Edit: 3/9/2006 3:55:31 PM EDT by theshootersden]

Originally Posted By bloodsport2885:
From the picture it looks like the bolt is actually riding OVER the mag, causing a partial feed. What type of mags are you using?



That's because its short stroking and the bolt isn't traveling back far enough to strip the top round from the magazine or possibly the bolt has a broken lug...
Link Posted: 3/9/2006 3:53:56 PM EDT
I know you said the mag catch seems to be working fine, but try tightening just a turn or two. You don't think it makes that much difference. I didn't either . Trust me, it does.
Link Posted: 3/9/2006 3:53:59 PM EDT
I have two "unknown" manufacturer mags.
Many are Okay's, Centers, and Two Colt mags.

5 of the Okays are new.

None of the mags had issues before.
Link Posted: 3/9/2006 3:55:35 PM EDT
First thought was "we miss Tweak"

But there are some capable hands int he Troubleshooter section (and here)

Link Posted: 3/9/2006 3:56:59 PM EDT
Did you look at the face of the bolt to see if it had any metal missing? Possibly a broken lug?
Link Posted: 3/9/2006 3:58:03 PM EDT

Originally Posted By bloodsport2885:
From the picture it looks like the bolt is actually riding OVER the mag, causing a partial feed. What type of mags are you using?



I had one jam that did that. My mags don't fit in there very tight
Link Posted: 3/9/2006 4:02:08 PM EDT
[Last Edit: 3/9/2006 4:14:13 PM EDT by theshootersden]
With an empty mag inserted into the receiver, when you pull the charging handle back, does the bolt catch grab the face of the bolt and lock or is it catching the carrier?

ETA: This is to check and see if the carrier is traveling back far enough...
Link Posted: 3/9/2006 4:06:53 PM EDT
The way you describe it does not sound like the mag catch, it sounds as tho something is binding the mag from latching, I would say the carrier or something to do with the carrier but I can not say for sure unless I saw it. It is not the bolt I wouldnt think as this wouldt mess with the mag seating. It is not the mag aas it does it with all mags. I think it is a safe bet it is something with the carrier or something touching the carrier. Would need to see for sure. Look for any abnormal wear on parts, trigger parts, bolt catch, all that is down there.
Link Posted: 3/9/2006 4:09:32 PM EDT
Have you changed the recoil spring?
Link Posted: 3/9/2006 4:34:17 PM EDT

Originally Posted By theshootersden:
With an empty mag inserted into the receiver, when you pull the charging handle back, does the bolt catch grab the face of the bolt and lock or is it catching the carrier?

ETA: This is to check and see if the carrier is traveling back far enough...



Yes.. an empty mag will lock into the reciever as normal without using force. pull the charging handle back and the bolt hold open acts as it should, locking the carrier back.


Originally Posted By theshootersden:
Did you look at the face of the bolt to see if it had any metal missing? Possibly a broken lug?



Nothing is missing from the bolt. Nothing is broken.


Originally Posted By fxntime:
Have you changed the recoil spring?



Yes I have. along with the original A2 stock buffer and spring.

Sorry for the slow replies, I am at a customers house repairing a PC and surfing ARFcom. (Bad bad me )
Link Posted: 3/9/2006 4:45:12 PM EDT
Link Posted: 3/9/2006 4:51:20 PM EDT
Hmmm... Its hard to say exactly with out being able to give it a good going over... I've seen gas leaks do the same as your experiencing...

Did you inspect the gas rings on the bolt to see if they are broken or worn?

Is the carrier key screws torqued and staked?

Is the roll pin missing that holds the gas tube in the front sight base?

Is the front sight base loose?

If you spray action cleaner into the gas tube at the receiver end while holding the rifle vertical, barrel down, does the fluid run out the end of the barrel?

Link Posted: 3/9/2006 8:24:40 PM EDT
Yep.. I'm a retard. Like I said.. I am not an AR guru.

What I thought the carrier key was was the bolt pin..

since I now know what a carrier key is. I noticed a fair amount of carbon buildup under it. so I grabbed a hex set and went to check if they were torqued down and to my surprise the front one wobbled. So I removed it, cleaned all the carbon off, torqued it down and peened it.

Correct me if I am wrong but a leaking carrier key can cause short strokes leading to FTF's?


But the mags are still hard (when loaded) to lock in the magwell.
Link Posted: 3/9/2006 8:46:49 PM EDT

Originally Posted By -RotorDemon-:
Yep.. I'm a retard. Like I said.. I am not an AR guru.

What I thought the carrier key was was the bolt pin..

since I now know what a carrier key is. I noticed a fair amount of carbon buildup under it. so I grabbed a hex set and went to check if they were torqued down and to my surprise the front one wobbled. So I removed it, cleaned all the carbon off, torqued it down and peened it.

Correct me if I am wrong but a leaking carrier key can cause short strokes leading to FTF's?
x10.putfile.com/3/6722540167.jpg

But the mags are still hard (when loaded) to lock in the magwell.



That would be your promblem
Link Posted: 3/9/2006 9:04:09 PM EDT
[sniffle] Did I mention I love you guys? [/sniffle]

Really.. I hope this cures all the problems.

Thank you for all the help!
Link Posted: 3/10/2006 4:45:36 AM EDT
[Last Edit: 3/10/2006 4:50:52 AM EDT by theshootersden]

Originally Posted By -RotorDemon-:

Correct me if I am wrong but a leaking carrier key can cause short strokes leading to FTF's?



Yup, that's why we suggested for you to check it to see if it was loose and leaking...

As long as you didn't scratch or gouge the surfaces when cleaning the carbon off, you have, without a doubt, fixed the short stroking problem... Let us know how it runs after you test fire it...


Originally Posted By -RotorDemon-:

But the mags are still hard (when loaded) to lock in the magwell.



Try loading the mags with only 28 rounds to see if that eases the insertion any...
Link Posted: 3/10/2006 6:12:43 AM EDT
[Last Edit: 3/10/2006 6:13:17 AM EDT by -RotorDemon-]
28 rounds I feel no difference. 0 rounds they insert easy and 10 rounds is what it originally felt like. (all 30 round mags)

Slide in a mag and give it a good slap and they lock. If all goes well or not I'll give a report after the Practical Rifle match. Saturday.
Link Posted: 3/10/2006 6:33:46 AM EDT
Yeah, sometimes downloading the mags helps but only after they are broken in and the spring tension is set, then downloading actually become noticeable... After the mags get loosened up from use they should be a little easier to slap into the magwell...

Good luck at the shoot Saturday...
Link Posted: 3/10/2006 12:23:23 PM EDT
Well, that's why you either slap the bottom of the mag after you insert it, or load with the BCG locked back, or both. I'll bet you're good to go now.
Link Posted: 3/10/2006 3:14:17 PM EDT
Good luck!
Link Posted: 3/11/2006 3:33:11 PM EDT
[Last Edit: 3/11/2006 3:45:33 PM EDT by -RotorDemon-]
Welp.. She ran flawlessly all day. Not one problem at all.

First time at Practical Rifle, I nailed a few 6" round targets at 290 yards.

Overall with the pros and rookies, I came in 46th out of 60. Today was more of a learning experience than competition. so I'll be ready to get a better score next time around.

I really appreciate all the help everyone has given.

THANKS!!!

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