Got my area 419 +4 and I'm pretty disappointed...
Its well machined, seems like a good design, follower doesn't bind, and yes - you can fit 10 6.5 PRC rounds in a MDT 10 round 308 (feed lips tweaked) with the +4 on it.
However, no magazine that I own has enough "spring height" to actually press the last round (or 2) to the top. Most end up at a totally goofy follower angle and even if you bend the shit out of the spring to give it more height, as soon as you fully load the mag it compresses the spring so hard that its back to its original memory position.
I'm a little surprised that -anyone- recommends these, for 3 different brands of mags (and both MDT 10 and 12 rounds) you couldn't successfully run the same number of round in it as you originally would have because it adds too much height to get the rounds to the top of the mag with sufficient spring pressure.
This seems like a fatal design flaw simply trying to do "too much", compared to a more traditional +2 base pad.
@MDT_Josh thoughts?