Because BCA is literally the bottom of the barrel, swirling with the flushing turds with ATI and Radical, etc, so on. There's no QC, everything is just slapped together and thrown out the door. The only QC is whatever batch QC their vendors might have done on some of the parts but even that is questionable.I'm 2 for 3 in BCA uppers
Cheap and when they work their great.
How an upper where the forward assist doesn't engage the bolt at all makes it to a customer I'll never figure out
I don't really understand why people who know how to build an AR flint this aggressively; you can likely easily build your own upper off various selected poverty level parts and end up with an outcome better than a BCA throwaway upper, for either marginally more or even slightly less vs BCA.