Received my 5 pack today.
A little bit more of slop in the mag well vs. stock, but all 5 worked fine in terms of function, feeding, and the bolt hold open operation.
Actually, one of my rifles hold the OEM mags a little tight, but these E-Lander A1A mags just pop in and out, so the extra play worked in favour for one of my rifles.
Only complaint is that the finishes on these magazines are a little crinkled, like the "orange peel look" of paint that's been sprayed on too heavily.
In comparison, the finish on the E-Lander M14 (5/20 rnd) and AR15 mags that I have are all super smooth.