So I've taken my 733 clone SBR out to the range twice now and have been experiencing disappointing intermittent failures to feed.
Thus far they have been pretty straightforward failures to feed as far as I can tell. It's occurred with a couple different Okay GI 30rounders which have functioned fine with other guns, including different uppers on this SBR lower (back before I Form 1'd it). The FTFs are happening about midway through the mag.
Gun has a Fulton C7 upper with M4 feedramps, a Spike's 11.5 lightweight barrel (Spike's was the only one offering a chrome lined 11.5 pencil barrel as far as I could tell), and a SOLGW BCG, BCM gas tube and Colt charging handle. Buffer is an H, and the spring is a standard Colt buffer spring.
Gun was lubed with Slip EWL prior to use. Temperature on both days was 20-25 degrees. Ammunition is Federal XM193. Seems to eject mostly around 3 o'clock or so, occasionally more like 2 o'clock to 2:30.
I'm wondering if perhaps I should be using a different weight buffer here. I don't know the gas port size on the Spike's barrel (I was told that was "proprietary information" when I emailed them, I really wish someone else offered the barrel profile I needed *sigh*...) So the gun could either be under- or overgassed for all I know. Or maybe the issue is with the feedramps?
Another odd thing is this:
This case is mangled. I would assume that this sort of case deformation would have caused a malfunction but the only malfs I had were straight up FTFs where the offending rounds fed, fired and ejected normally after remediating the FTF. This case looks more like one that failed to eject and got crushed by the BCG coming forward, and I didn't have any FTEs. So I didn't notice this happening while shooting. It is possible that this isn't even from my gun, but it has the same headstamp as my other brass and was in the same spot as my other cases, where I don't believe there was any pre-existing brass on the ground.
So I don't know what relevance, if any, this has, but I thought I'd mention it. But like I said, perhaps this wasn't even from my gun.
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