AR Sponsor
Posted: 12/30/2007 8:04:39 AM EDT
| I just got a new bushmaster and it has problems feeding and jamming. Sometimes it will jam when pulling back charging handle to load..the bullet appears to be hung in the feed ramps, and you have to remove the magazine. Other times it jamms between shots. It looks to me like the bullets are hanging on the magazine..just as the bullet leaves the magazine(on the rim). Any ideas? |
| OK I looked at that link. I'm not sure about this one. I'm pretty sure I could figure this out if I had the AR in my hands. I guess I would start by taking some measurements and comparing this to one of my AR's that I know works. Any chance you can get another AR? |
|
Shotgun the upper open and take a good look at the upper receiver front section just below the barrel ramps. Are there signs of mag low feeding (small dents with copper color marks)? Since I didn't see what ammo you are running, if you are running Wolf (coated steel cases) try another brand to break the rifle in. If the rifle was not cleaned and the upper bearing surfaces of the receiver not correctly CLP lubed, then you could be causing a bit of short stroking. Also to point out, the short test should be the first thing confirmed to start trouble shooting the rifle. As point out above, not cleaned or lube, Wolf ammo in your rifles case, or just a loose carrier key screws could all be a fault if this is an action short stroking issue. Now if there is no signs of the mags low feeding (dents below the barrel feed ramps), and the rifle is stroking correctly (read will lock the bolt back on the last round fired out of the mag), then suspect that the FP collar is catching on the top of the hammer, and you may need to do a bit of tweaking to the FP collar (reduce the collar OD radius to be flush or slightly below the carrier ramp via a drill and file), and the hammer as well (rounding the top edge of the hammer contact pad at the bottom of the top L cut corner so the FP collar makes contact into the pad of the hammer, and not caught on the edge of it, which locked up the B/C in the upper). |
|
A mag low feed is instead of the round being feed out of the mag straight into the barrel feed lips, the tip of the round is first shoved into the upper receiver below the feed ramps, then the tip dance upwards into the ramps (read takes a great deal of the forward momentum of the B/C out of the math, and the B/C may not have enough forward tension left for a full lock up/clean feed. 95% of the time with mag low feeds, it's the B/C that is not stroking correctly at self-reloading. A dead giveaway to short stoking problems are the Bolt will not lock back on the bolt catch after the last round has been fired out of the mag). |
| the bolt locks back after last round. Its mainly the first shell you load(by hand) with charging handle that jams. It does jam between shots with cheap ammo though...and the jam appears the same, the pont of the bullet rammed into the section below feed ramps. Only way to unstick is to pull the magazine out. |
OK hang on. Are you riding the charging handle? If so you shouldn't. Pull the charging handle all the way back and let it go. |
| no..not riding it, pull it back, let it go..then the shell gets jammed. Then if you pull the magazine out, re-inset it, it might work for several shots..im goinf to try non hollow point ammo and see what it does. Also ordered different followers. The magazines are brand new c products with orange followers. I ordered green followers to replace them |
|
Pull the buffer and recoil spring out of the receiver extension and check the end of coil winds on the spring for burs that may be scrapping down the inside of the tube, and the buffer bumper roll pin extruding from the sides of the buffer tube that may be hanging out and catching the spring. If found, use a file and remove such. Before reinstalling the buffer and spring, lube the parts with CLP. Regarding the bearing parts of the upper, you are lubing them with CLP? If not, then the short version of this is to just spray down the B/C with BreakfreeCLP (inside and out), give the B/C a quick shake, the once you have it back in the rifle, work the action a few times to allow the CLP to migrate to the other upper bearing surfaces of the upper receiver. |
|
I am having a similae problem as the OP. From a full mag, charging a round leaves the round half in the mag. If I can get it to feed, subsequent shots result in the same until enough rounds have been expended (7-10) that mag spring pressure is reduced. Denny at GTS has been sent the upper, where he reinstalled the gas block against the barrel shoulder (operator barrel). I got the upper back and I'm still having the same problem. Rifle is cleaned and lubed correctly. FP is riding in a shrouded M16 carrier. Malf occurs with several different mags (all known to be 100%) Buffer and spring are from an unknown maker (might be the issue). Buffer spring is approx. 1" longer than one in a functioning (runs like a top) AR. I'm at my wits end with this thing... I'll try and make it to the range today and try the upper on another lower (again) to see what the problem is... Any ideas would be appreciated. |
|
ok..i think i found the problem. Now if yall can tell me the solution. ..I went to the range again, after cleaning and lubing, checking the buffer. jammed right off the bat, feeding the first round. After messing with it, i found if i push the magazine towards the muzzle(forward) it works great and will feed every round. I have been reading and searching, and found this to be a common problem, but the only fix i read, is putting a matchbook in between the magazine and mag well. Surely there is a better fix??? Any help appreciated Thanks JR |
| Mine too was brand new jrgreene, and I experienced some of the same problems that you describe. The mags did not 'feel' tight in the well, so I took 2 turns (CW) on the mag eject and the mag felt much tighter. Granted, I tried several things at once, so I can't be sure that tightening the mag in the well was the fix, but it really is simple and unlike unringing a bell, you can untighten the mag if it doesn't solve your problem |
Did it work? |
AR Sponsor