I rec'd one of the 5 mags offered for testing here  by Dameien at Tapco. Got it yesterday along with a Tapco T-shirt(Thanks!) and compared it to a Magpul as that's the gold standard right now. It looks good and the floorplate is easily removeable. The anti-tilt follower works smoothly up and down. It does not have the internal rib to guide the bullet tips like a Magpul. I then proceeded to test the fit in four different lowers. It seated and would drop free from a Tactics LLC and a DPMS. Seated but would not drop free from a Stag or RRA. In all fairness, I should note the Magpul doesn't seat  in my DPMS lower w/o a firm smack. Loaded it w/ 30 rounds of Silver Bear. The spring is fairly stiff.  But, the mag does unload very smoothly unlike USGI aluminum mags. Left the mag loaded overnight. Got up this AM and downloaded to 28 and went to my buddy's farm to try it. Two FTFeed out of the mag. I'll continue to test in the DPMS lower IF BUSHMASTER SENDS ME THE BARRELS I ORDERED IN NOVEMBER. Anyway, thanks Dameien at Tapco.

Why the download to 28 rounds?