Well, I finally got to the range yesterday and must say I am quite happy with the accuracy I'm already seeing out of my 18" BCA upper with only 40 rounds of break in. Here are two 4 round groups at 100 yards (don't mind the two shot zeroing groups on the one target):
20170904_144614.jpg
20170904_144622.jpg
Unfortunately, the upper was having reliability problems, or so I thought. I have two magazines; an ASC (10 rds I think) and an AA 17 rounder. The first 8 rounds cycled out of the AA mag just fine. Then I tried the ASC and was getting bolt over base FTF malfunctions nearly every round, so I set that mag aside for now. When I went back to the AA mag, however, I started having FTFs where the bolt would entirely fail to strip a round out of the magazine every other shot. It seemed like an obvious short stroke to me, and I became very worried that the upper is under gassed (.70 gas port on midlength 18" barrel is on the small side to my understanding).
But, a strange discovery later last night alleviated my fears! As I prepared to clean the gun and check culprits for under gassing (gas block alignment, etc), I heard a strange rattle noise when I tilted the gun. I realized it was coming from my buffer tube, which I wouldn't ordinarily open for a routine cleaning. When I pulled the buffer and spring, this is what I found!:
20170904_192553.jpg
I haven't had a chance to go shooting again to confirm the hypothesis, but I think it's pretty safe to assume that the loose weights in my buffer tube were causing the short stroking! It would also seem to explain the bolt over base malfunctions if the bcg was moving to fast for the next round to move up after it recoiled against the empty buffer. It's bizarre, but I'm actually relieved that the upper itself seems fine and at the very least I learned my lesson on buying cheap buffers.
So, at the end of the day, I think this BCA upper is going to be a heck of a shooter, especially for the price! If it feeds reliably and continues to group well at my next range session, I'll be fully prepared to endorse BCA based upon my experience at least.
20170904_144614.jpg
20170904_144622.jpg
Unfortunately, the upper was having reliability problems, or so I thought. I have two magazines; an ASC (10 rds I think) and an AA 17 rounder. The first 8 rounds cycled out of the AA mag just fine. Then I tried the ASC and was getting bolt over base FTF malfunctions nearly every round, so I set that mag aside for now. When I went back to the AA mag, however, I started having FTFs where the bolt would entirely fail to strip a round out of the magazine every other shot. It seemed like an obvious short stroke to me, and I became very worried that the upper is under gassed (.70 gas port on midlength 18" barrel is on the small side to my understanding).
But, a strange discovery later last night alleviated my fears! As I prepared to clean the gun and check culprits for under gassing (gas block alignment, etc), I heard a strange rattle noise when I tilted the gun. I realized it was coming from my buffer tube, which I wouldn't ordinarily open for a routine cleaning. When I pulled the buffer and spring, this is what I found!:
20170904_192553.jpg
I haven't had a chance to go shooting again to confirm the hypothesis, but I think it's pretty safe to assume that the loose weights in my buffer tube were causing the short stroking! It would also seem to explain the bolt over base malfunctions if the bcg was moving to fast for the next round to move up after it recoiled against the empty buffer. It's bizarre, but I'm actually relieved that the upper itself seems fine and at the very least I learned my lesson on buying cheap buffers.
So, at the end of the day, I think this BCA upper is going to be a heck of a shooter, especially for the price! If it feeds reliably and continues to group well at my next range session, I'll be fully prepared to endorse BCA based upon my experience at least.
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