User Panel
Posted: 2/7/2006 6:12:20 PM EDT
Don't know what the hell is going on with this thing.. I try to insert any of my 20 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 Shoot. and today 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. WTF?! Edit: 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. |
|
new mags?
proven mags? mags work in another ar? Mag catch not bent/tweaked in any sort of way? |
|
When the rifle was working properly, it ran every mag flawlessly.
I haven't tried them in another rifle, the problem has to lay within this one. AFAIK themag catch is working properly. with the upper off of the rifle.. they insert, lock and drop free as they should. Edit: 500 posts. |
|
But 20 of them?????
Edit: 21, I just opened a new USGI out of the wrapper and I can't get it to lock with the upper on. |
|
So, mags out of the Question, I'd be replacing the mag catch and the bolt stop if I were you. |
|
|
yeah - check the bolt stop.
Shot gun the upper and push the bolt stop. does it move freely? good spring? not binding? Not broken, bent, chewed up, siezed in place? You haven't been dryfiring just the lower have you? w/ out the bolt in the way the hammer will impact the bolt stop and break it. |
|
It may be the mag catch is worn or dirty and the 20 rounders have a slightly different mag slot than the 30 rounders. Seperate the upper from the lower and insert both the twenty and thirty round mags noting the slop while pushing up and pulling down on the mag.
ETA: After looking at the picture I'd make sure the bolt stop is working freely and stays down with the follower lowered. The spring may be broken too. |
|
I'll get a punch set and take the bolt stop off. 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.
Hmmm.. I forgot to add in the first post that 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. almost like a stovepipe in a .22. I had better stop and get some snap caps so I don't have a KB if the bolt decides to punch the primer. Edit: I'll get a pic of what it does here in a minute. Sorry for the blurry pic. |
|
Hows the key on the carrier? If it came loose, wouldn't it allow the bolt to ride up like that?
Either way, I feel it's narrowed to the bolt stop, mag catch or the carrier now. Keep at it, I'm sure you'll find it and the light will come on |
|
good idea with the bolt key. is it a bushmaster? |
|
|
MR.Demon is saying any one of his 20 mags not one of his 20 round mags.
My .02 is that your spring in the mag catch is broken and or bitched up. carrier key or bolt are something bad. did you get a good look at the bottom side of your bolt the big brass mark on the bolt stop makes me go huh. maybe it is missing part of the lug so it isnt picking up rounds like it should. Hard to say take some more pictures of the bolt/carrier magwell/catch inside out side etc. Good luck |
|
Damn! I'm gonna have to start reading with both eyes. I'd still look at the mag catch and bolt stop. If the mag catch is allowing the mags to be too high it may hinder the bolt travel as well as push the bolt stop up. or not. |
|
|
First questions to ask:
The cycle of operations, and where failures occur in said cycle can be used as a troubleshooting guide. See www.armalite.com/library/techNotes/tnote50.htm. Anything that slows the bolt down (hammer drag, fouled upper, mainspring or buffer drag, or a sticky bolt stop) can cause a short cycle, resulting in the bolt-over-base feed failures you're seeing.
If all else fails, it never hurts to go back to the manual. AR15.com Copy of M16 Operator's Manual |
|
THAT could very well be it.. Nothing was changed before the january shoot. and watching the mag it does ride very high. probably 30lbs of pressure will get the mag to latch and it is SOLID. I tore it all down today, everything minus the barrel, forward assist, dust cover and the bolt hold open. the last time I shot it before the jan shoot, the weather was in the 70's and it functioned great. I ran 600 rounds through it in seperate mags. I'll take it out next week, hopefully warmer. THANKS for the info and the links! |
|
|
I'll be the first to say it......................................................Get an AK!
|
|
I own a Saiga in x39 So.. I kinda do. It has never failed to fire on me. |
|
|
What kind of buffer are you using and what kind of FSB? Yes, they can cause problems in the cold but work fine in the summer heat. Short stroking with XM885 is a serious problem because that is powerful ammo. |
|
The FSB is the stock Bushmaster (Like I said I'm not a know it all)
As for the stock buffer(s) I have a Tapco 6 position and the DPMS A2 stock The A2 stock (spring and buffer) functioned flawlessly, Bumpfire and all The Tapco stock (spring and buffer) functioned alright, no problems with loading, cycling, it didn't bumpfire as well. They worked fine before this problem. I've swapped all the crap back and forth. no fix. I'm damed sure that when I find the problem with why the mags dont like to lock without excessive force (not with a hammer ) then that would be the source of my problems. |
|
The picture of the scratch looks like a bolt lug is dragging low. Have you pulled the bolt to verify it is not cracked?
|
|
well, anything |
|
|
|
Told ya so??????? Hope that's it!!!! |
|
|
Still way to hard to put a loaded mag in. Unloaded ones lock as they should. BUT. I think it's a good start, with gas leaking around the key (Noted carbon buildup around it) I bet that can cause short strokes and FTF's |
||
|
and it is a bushmaster... shocked. just shocked. |
|||
|
Perhaps you should try it with a Colt bolt carrier. |
|
|
That is a good point TF. The angle of the scratch looks like the bolt head was turning while making that mark. Does the bolt move in and out smoothly when out of the carbine? CH |
|
|
Couold your DPMS lower be out of spec? Location of mag catch a bit too low?
ETA: If you're around the Salem or Albany/Corvallis area I'd be happy to let you install all your stuff onto one of my complete lowers. |
|
Just thought I should mention: That scratch mark is absolutely normal. Look carefully at the bolt catch -- its wedge shaped, with the taper starting from towards the barrel, and the sharp edge back towards the stock. When the last round is fired, the magazine follower pops up and presses on the protrusion on the bolt catch, lifting it up. When the bolt tries to go forwards after its recoil, the face catches on the flat face at the rear of the bolt catch. Now, having loaded the last round into the chamber, the follower is up, pushing the bolt catch up to its locking position. So, if its going to catch the bolt, it has to be higher than the bolt ... which means that it is going to have to be pushed down for the bolt to pass over it on the recoil. That is whay its wedge shaped. The bolt pushes it down as it comes back, once the bolt is passed it pops back up to catch the bolt on its way back forwards. If you doubt me, put an empty magazine into your AR and slowly pull the charging handle back. You will see the bolt head push the bolt catch down as it passes back over it. That is what causes the scratch. It seems that not all bolt catches are created equal, some are made of harder material, and some have harder parkerizing, so some show up the scratch more than others. Don't worry about this mark -- other than to let it remind you that you should lubricate the top of the bolt catch from time to time. |
||
|
Welp.. Got back after PR, and would like to thank everyone for all of the information, help and assistance.
The AR worked flawlessly today! |
|
Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. One new winner* is announced every week!
You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers.
AR15.COM is the world's largest firearm community and is a gathering place for firearm enthusiasts of all types.
From hunters and military members, to competition shooters and general firearm enthusiasts, we welcome anyone who values and respects the way of the firearm.
Subscribe to our monthly Newsletter to receive firearm news, product discounts from your favorite Industry Partners, and more.
Copyright © 1996-2024 AR15.COM LLC. All Rights Reserved.
Any use of this content without express written consent is prohibited.
AR15.Com reserves the right to overwrite or replace any affiliate, commercial, or monetizable links, posted by users, with our own.