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Posted: 9/4/2016 1:40:35 AM EDT
 [/URL]" /> " />Longtime reader, first time poster. I am working with a Bushmaster Carbon 15 that I have about 3,000 rounds of flawless operation through. I have only ever fired new manufacture brass factory loads, and, and used high quality magazines in this weapon. For fun, I decided to put a slide fire stock on it, and took it to the range. It was super fun, I was freaking out the people on the lane next to me, having a good old time, when I got my first mis-feed with this rifle, under the fake automatic fire. I cleared it, got a few more rounds through it in regular semi-auto to make sure things were kosher, and then switched back, and it happened a couple more times when I was slide-cycling. The mis-feeds were getting jammed on the way up the ramps, and it was cycling so hard that it rammed the bullets into the cartridges. When I went back to semi-auto, it seemed to function normally again. Ammo/weapon/mag combo are all tried and true in this setup for semi-auto.
1.) Has anyone else had slide-fire issues with a Carbon-15? Is it too light for fake automatic fire? 2.) Would a nice nickel-boron full auto BCG solve this issue? 3.) Is the damage to the area below the feed ramps an issue? Look forward to advice from the hive-mind... |
Lets start here, being that you have a M-4 extended ramps barrel in the no M-4 upper receiver, and this is half of the problem.
Note, with a plastic upper receiver, The OK is not fine in the lower right hand corner, since if you do get a low feed to strike the face of the upper receiver below the feed ramps, then instead of a light peen of the aluminum metal of a metal upper receiver, the unsupported plastic edge of the plastic upper receiver will crack instead. As for bump firing, since you have to let the rifle free move with only a fixed position to the trigger, this means moving rifle is have less resistance against a fix item like your shoulder and in fact making it harder for the rifle to cycle correctly as well. To add to this, the same problem is happening with mass of the rounds in the mag, which makes it even harder for the mag spring/follower to get the top round in the mag tight up against the bottom of the feed lip in the mag before the bolt goes to strip the top round, and ends up with less than stellar mag feeds as well (low mag feeds out of the mag). So bullet tip damage to the upper receiver, wrong barrel extension in play. Since the damage is already done, would just do the extended ramps on the upper receiver to match up with the M-4 barrel extension in play. Low feeds out of the mags, would start with pulling the mags completely apart to first start with a CLP cleaning of all the parts, then double check to make sure that the mag springs still had good tension to them, and if needed, mag spring replaced (or just replace the mags if the bodies are showing signs of cracking, the mag lips bent out of shape. Also, would check to make sure that the threaded section tip on the mag catch assembly was flush with the face of the mag release button. As for the bump fire devices, you do understand that there is a reason that BATF allows such to be sold without a tax stamp. Hence is it was reliable to create full auto controlled fire with no fear of it doing damage to the rifle, no way in hell that it would be allowed to be sold without a tax stamp in the first place. Point blank, since the device was causing problems, such as the damage to the upper receiver from the device causing low feeds out of the mag, get bump fire on the phone to see what they will do in regards to replacing the damaged parts caused by the use of there device. |
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Is the upper made from carbon fiber or is it aluminum? Recently BM had been building their CF rifles with an aluminum upper and carbon lower due to this problem. If it's carbon fiber, the rifle is done and upper needs either needs sent back to BM or you can replace it with an aluminum one.
I had a carbon fiber BM rifle years ago. It developed pock marks below the extension(just like yours) and rounds would get caught up causing FTF. Problem got increasingly worse. Sent it back to BM and they polished the carbon fiber feed ramps, making it even worse. Then I sent a lengthy letter to them that plastic extended ramps didn't hold up(obviously). Sent back again, rifle came back with an aluminum upper w/M4 cuts and an aluminum lower. |
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Thanks for the feedback! I am pretty disappointed that BM miss-matched the extension and the upper that way. I think you are correct, the mags are new and springy, but could not keep up with the bump fire feed demands. This in conjunction with the plastic upper caused the damage. That went from lark to bummer in a hurry. This rifle is well past the 1 year and 10 day warranty Bushmaster offers, so I am on my own with it. Perhaps I can Dremel out the damage, and it will feed ok in semi-auto until/unless I replace the upper. On the positive side, I will now be forced to buy another $900 rifle so I can use my $185 bump fire accessory. No choice in the matter....
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Thanks for the info, sounds like you had the exact same issue. It is definitely the old style plastic/carbon fiber type. Were you still in the 1 year warranty period when they replaced your upper? Yes. I had only had the rifle for a few weeks then it was sent back. Got it back 3 weeks later, shot it, it malfunctioned, and was again sent back that week. They replaced the upper and lower with aluminum. I would still get in touch with them. Worst case scenario is you get a stripped upper. |
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