Hello all. First off, hope you have had a merry Christmas!
So, I have a Colt Match Target H-Bar AR-15. 100% completely unmodified. And I am having a problem with it short-stroking/FTF. It will also occasionally fail to extract, but that's a more random thing and relatively infrequent occurrence. The short-stroke/FTF is the problem I'm concerned with right now. I'll give a comprehensive (albeit long) description of what I've gone through troubleshooting thus far.
Ammunition: I'm shooting the black box Wolf 55 grain ammunition. I already know the comments I'm going to get about that, but quite frankly, I don't care. I don't want to sound snooty or know-it-all, but I think that a Colt gun should shoot Wolf. My immediate family has multiple Colt AR-15s, and all of them shoot it 100%. A while back, my father spoke with Colt, and they told us that if their gun would not shoot Wolf, then something was wrong with the gun. Therefore, the solution to my problem is NOT going to be shooting more expensive ammunition. That simple. But I digress. So:
1. Completely stock/new gun. Shot roughly 400-500 rounds through it perfectly with the exception of a few failure to extract, but that was something I still chock up to being a new gun with no break in. The FTF problem began relatively quickly (as in it was not gradually over a long period of time), definitely within 100 rounds or so. It would do it every single round, more or less.
2. Swapped buffer and spring from my dad's identical (and fully functional) Colt. Made no difference whatsoever, so we swapped them back.
3. Swapped bolt carrier group assembly from my dad's Colt. My dad's gun shot fine for the 100ish rounds that were shot through it. My gun shot fine for 150ish rounds, then went right back to FTF. So we swapped both back.
4. Sent the gun off to Colt. Not 100% sure what they did other then polish the chamber and other areas in the upper receiver, but it was supposed to be good to go according to them. Got the gun back, and shot at least 200 rounds through it with no problems. Then it went right back to FTF.
It was at this time that I repeatedly tested it for short stroking, as well as if magazines had anything to do with it. Using the 1-round in magazine test, it short stroked EVERY round. I tried this test with multiple magazines, including the stock 9-rounder, several Colt 30-round mags, a Magpul PMAG, and 2 20-round Brownell's mags. Identical results with each magazine, which effectively rules out magazine problems.
At this time, we also polished the chamber/upper quite thoroughly with the cleaning brush on a drill.
I also decided to try some hotter ammunition, just to see. Shot some Canned Heat and Hotshot brands brass, and it actually cycled it perfectly. Did the 1-round short stroke test numerous times, and found it to be working flawlessly. Loaded up a 30 round magazine with Canned Heat/Hotshot, and also threw in 3 Wolf rounds randomly in the mix. It would shoot and cycle the brass perfectly, but on EVERY single Wolf round, it would eject it, and then fail to load the next round. Because of this, I reasoned that there must be a gas/pressure issue somewhere that was being masked by the hotter brass ammunition.
5. Swapped barrels with my dad's Colt. We were thinking that maybe there was a problem with the gas block, and that it would also eliminate some kind of problem in the chamber. It shot roughly 80 rounds out of various magazines flawlessly. Then, almost like a light switch, it went right back to FTF/SS every shot.
6. Swapped the gas tubes from my dad's Colt (thinking that maybe there was some microscopic defect that we couldn't detect by the naked eye). So I now have both his barrel and gas tube. I shot 10 rounds out of it, had one FTF and it definitely short stroke on the last rounds. So it isn't FTF on EVERY round now, but it definitely still isn't 100%. I'm going to put a few more rounds through it tomorrow, and see if it gets better or worse.
And that's where I'm at right now. We are pretty much at a loss on this issue. The ONLY component that hasn't been swapped from a working gun at this point is the upper. I think we're going to try this tomorrow or sometime soon. But other than this, we don't know what else to do other than send it back to Colt.
So, after reading that novel (and I thank you for doing so), do you have any suggestions? I welcome all of them.
Thanks!
So, I have a Colt Match Target H-Bar AR-15. 100% completely unmodified. And I am having a problem with it short-stroking/FTF. It will also occasionally fail to extract, but that's a more random thing and relatively infrequent occurrence. The short-stroke/FTF is the problem I'm concerned with right now. I'll give a comprehensive (albeit long) description of what I've gone through troubleshooting thus far.
Ammunition: I'm shooting the black box Wolf 55 grain ammunition. I already know the comments I'm going to get about that, but quite frankly, I don't care. I don't want to sound snooty or know-it-all, but I think that a Colt gun should shoot Wolf. My immediate family has multiple Colt AR-15s, and all of them shoot it 100%. A while back, my father spoke with Colt, and they told us that if their gun would not shoot Wolf, then something was wrong with the gun. Therefore, the solution to my problem is NOT going to be shooting more expensive ammunition. That simple. But I digress. So:
1. Completely stock/new gun. Shot roughly 400-500 rounds through it perfectly with the exception of a few failure to extract, but that was something I still chock up to being a new gun with no break in. The FTF problem began relatively quickly (as in it was not gradually over a long period of time), definitely within 100 rounds or so. It would do it every single round, more or less.
2. Swapped buffer and spring from my dad's identical (and fully functional) Colt. Made no difference whatsoever, so we swapped them back.
3. Swapped bolt carrier group assembly from my dad's Colt. My dad's gun shot fine for the 100ish rounds that were shot through it. My gun shot fine for 150ish rounds, then went right back to FTF. So we swapped both back.
4. Sent the gun off to Colt. Not 100% sure what they did other then polish the chamber and other areas in the upper receiver, but it was supposed to be good to go according to them. Got the gun back, and shot at least 200 rounds through it with no problems. Then it went right back to FTF.
It was at this time that I repeatedly tested it for short stroking, as well as if magazines had anything to do with it. Using the 1-round in magazine test, it short stroked EVERY round. I tried this test with multiple magazines, including the stock 9-rounder, several Colt 30-round mags, a Magpul PMAG, and 2 20-round Brownell's mags. Identical results with each magazine, which effectively rules out magazine problems.
At this time, we also polished the chamber/upper quite thoroughly with the cleaning brush on a drill.
I also decided to try some hotter ammunition, just to see. Shot some Canned Heat and Hotshot brands brass, and it actually cycled it perfectly. Did the 1-round short stroke test numerous times, and found it to be working flawlessly. Loaded up a 30 round magazine with Canned Heat/Hotshot, and also threw in 3 Wolf rounds randomly in the mix. It would shoot and cycle the brass perfectly, but on EVERY single Wolf round, it would eject it, and then fail to load the next round. Because of this, I reasoned that there must be a gas/pressure issue somewhere that was being masked by the hotter brass ammunition.
5. Swapped barrels with my dad's Colt. We were thinking that maybe there was a problem with the gas block, and that it would also eliminate some kind of problem in the chamber. It shot roughly 80 rounds out of various magazines flawlessly. Then, almost like a light switch, it went right back to FTF/SS every shot.
6. Swapped the gas tubes from my dad's Colt (thinking that maybe there was some microscopic defect that we couldn't detect by the naked eye). So I now have both his barrel and gas tube. I shot 10 rounds out of it, had one FTF and it definitely short stroke on the last rounds. So it isn't FTF on EVERY round now, but it definitely still isn't 100%. I'm going to put a few more rounds through it tomorrow, and see if it gets better or worse.
And that's where I'm at right now. We are pretty much at a loss on this issue. The ONLY component that hasn't been swapped from a working gun at this point is the upper. I think we're going to try this tomorrow or sometime soon. But other than this, we don't know what else to do other than send it back to Colt.
So, after reading that novel (and I thank you for doing so), do you have any suggestions? I welcome all of them.
Thanks!