AR Sponsor
Posted: 2/21/2015 6:00:13 PM EDT
|
Guys,
I have a Doublestar AR15 with A1 upper, in carbine length, with pencil barrel, yes it is older but has seen not heavy use. I will lay out the problem and what I have done thus far: Problem: On a full mag (20 or 30 rounds) cannot get the first round out of mag and into the chamber (have to rack it 2 times usually), tends to have double feeds or doesn't strip next round once first round is chambered and fired. It will sometimes go into battery without a round chambered. So far I have: Cleaned, lubed, Replaced the buffer spring, used Pmag's (20 and 30 rounders), USGI mags (20 and 30 rounders), Colt labeled 20 rounders and still have the problem. Considering a new bolt carrier group, new buffer and another buffer spring, new extractor and O ring and spring (yes this does not seem the problem but hey why not!) Any input would be helpful. Thanks in advance ! Kevin |
| I would experiment with putting pressure upwards on the bottom of the magazine when closing the bolt. Does this help? If so, I suspect you have a worn and/or out of spec mag catch that is letting the magazine ride too low in the magwell, allowing the bolt to slide over the top of the cartridge in the magazine when chambering. Also verify that the mag catch is threaded all the way into the mag catch button, providing a good solid lock on the magazine when inserted. Good luck! |
|
Pull the bolt off the carrier and with just the carrier and key, dry fit it to the upper receiver, without first, then with the charging handle in play .
The sides of the key should not be binding down the upper receiver slot/top to the charging handle, and an inch before the front of the carrier touches the back of the barrel extension, should be able to fell if the gas tube is correctly aligning with the carrier key. Also, this will allow you to make sure that the charging handle pawn is not protruding into the upper receiver void and binding the carrier in the upper as well. On the B/C, start with making sure that the stop collar of the firing pin is not proud of the carrier ramp just in front if it. The OD of the stop collar on the FP should be flush, or slightly below the ramp of the carrier. If the FP collar is proud of the ramp, then it will catch the top of L cut on the hammer firing pin contact pad to hand the B/C up every time. On the recoil spring, let start to make sure that its the right length. If a fixed stock, then should be 11.75", and if a telescoping butt stock, should be 10.5". While you have the spring in hand, take a file to the end of spring winds to remove any burs that may be scrapping down the inside of the tube, or against the side of the buffer. On the buffer, check the buffer bumper roll pin to make sure that is not protruding out the sides of the buffer. As for barrel, if you have not scrubbed the chamber by hand with CLP and a chamber brush, now would be a good time to do so. Now, time to check for gas leaks. Piece of tubing to put on the end of the gas tube in the upper receiver, CLP around the gas tube to FSB, and FSB to barrel front and back, charge the tube/gas tube with about 100lbs of air, and look for leaks up at the FSB. On the B/C, put CLP around the key to top of carrier, hold the bolt in, and pressurize the front of the key to make sure that the key in not leaking from the top of the carrier where it seated against. Also, need some back ground on the upper, since if they upper was used to run a 22lr kit, could be that the barrel gas port, FSB gas passage, and even gas tube are jammed solid with lead scrapping from the 22lr ammo. If such is the case, then the FSB and gas tube need to be pulled to clean the lead out of the barrel gas port, the FSB gas passage, and gas tube. If no 22lr was shot through the barrel, but the barrel was left to sit long enough, then the gas system may just be clogged with cleaning and fouling crap instead. This standard fouling is easy to resolve. Just shoot CLP down the gas tube from inside the receiver, and leave the rifle muzzle down for a few hours. CLP had a good cleaning against it in, and will dissolve such fouling no problems in a few hours. Before shooting the rifle again, just run some dry patches down the barrel bore to get the CLP/lube out of it, and as for the fouling/CLP still in the gas tube and FSB, leave them alone and they will be blow back into the carrier during live fire to clean such out the next cleaning of the rig. |
AR Sponsor