AR Sponsor
Posted: 10/19/2006 6:26:16 PM EDT
| Hey guys. I have been having some problems with my AR. I recently switched from an A2 upper to a CMT flat top. I also put a new barrel on the CMT. Since the switch I have been having problems with my rifle. I seem to be having troubles. When it happens, the rifle locks up and I have to pull very hard on the charging handle to get the BCG to move. Some times there wont be a round in the chamber and sometimes there will be(and the hammer fell but did not set it off) and is very difficult to extract. I was wondering if you guys had any ideas. |
GAS key is the first thing i checked. |
|
Since this is a new upper, how many rounds through it? Have you tried running it very wet to see if it will run correctly? Is the chamber clean and smooth? A lot can happen in the first few hundred rounds through a new barrel, many of them not so good. Good news is most are easily fixed. A few things to check. - Ammo. Have you changed recently? If so, try some that has easily chambered bullets, Federal AE 55gr is fairly cheap and feeds well in most all chambers. Also, when you remove a round that doesn't ignite, check the primer for a very light strike (or none) and check the case and bullet for signs of where either might be sticking in the chamber. - Chamber. Clean it thoroughly and verify that you can drop a round into the chamber without having to push it in. It should also drop out easily if you point the muzzle up. If this doesn't work, check the throat and leade and make sure you don't have a buildup of carbon in the throat area of the bore. This is not uncommon in almost new barrels and will cause rounds to not chamber fully. - Inspect the chamber to make sure it is smooth inside, no reamer marks, etc. If it is chromelined, are there any edges/corners when chrome has left any buildup? A rough chamber will often work ok, but sometimes too much friction will cause incomplete feeding and sticking. If a hand fed round binds in the chamber, a little polishing will go a long way. There could be a lot of things going on, but since you have another upper, you can easily rule out the lower, mags, ammo, and other common use components if they work fine in the other upper. Make sure you keep a lot of lube on the carrier when you are shooting in a new upper. The fact that you occasionally have no round in the chamber after a cycle indicates that the carrier is not moving back far enough to clear the magazine and holding down the top round in the mag. When a new round is stripped, this can also cause an incomplete feed due to friction absorbing some of the forward energy of the carrier. try hosing the carrier and bolt down with CLP in some form (the cleaner component helps a lot when uppers are new). Shake off the excess and put it back in wet. Cycle a few times by hand and then try with a mag. If wet-lubing works, just shoot it wet for 500 rounds or so and then re-evaluate function. By then the upper should be slick enough to function with standard lube regimen. Do get in the habit of occasionally shooting only part of a mag, stopping, and checking to make sure you can easily clear the chamber. if you still have a sticking problem, figure out if it is the bullet or the case and readdress that issue. |
AR Sponsor