Somehow, I don't remember ever seeing them, and it looks like Academy has the on sale with free shipping over $25. Worth the bother?

I just bought 3 from Academy to try out. Read some reviews and they seem to be favorable. US made of Dupont milspec polymer, they have an anti-tilt follower and an oversize bolt stop also they are technically a 31 round mag to allow trouble free closed bolt reloading with 30 rounds in them and a stainless spring. Finally they have slimmer baseplate to fit pouches better than a Pmag, two drainage holes and a dot grid on the base for marking. For the same price as an $8 aluminum mag I figured WTH....

Thanks for the reply, sounds like they are working for you. I just was not familiar with them...

I have some and posted a short review few months ago.
Zero issue so far on different AR, M16 and Tavor.

I haven't tried their mags yet, but their other equipment is well made and so far seems durable.

I have one.  It came with my new AR.  It will not lock the bolt open when  empty.  The follower does not travel high enough.  The last round is shot and the bolt still goes forward.

I'd  take the mag apart and see whats hanging up the follower. MFT's have an over sized bolt notch and stop so if it isnt coming up enough to lock back the bolt then maybe there's some flash or sprue inside the mag hanging it up.