I’m happy to report that the magazines for the 75b series fit in the SAR K-12 sport x just fine. This model does not have the flaired magwell. I used regular factory mags with metal base plates, factory SP-01 extended mags and aftermarket mecgar mags with rubber base plates and extended +2 base plates. They all worked flawlessly and function correctly. The slide locks back for all of them and feeding was fine. I also used the SAR mags in my SP-01 and they worked in that fine. The only thing I noticed is the SAR mags are ever so slightly longer than the CZ mags so there is the smallest of gaps between the magazine base plate and the bottom of the grip frame of the CZ when using the SAR mag. I’m talking about a fraction of an inch. Maybe not even a 32nd of an inch. Conversely, when the CZ mags go into the magwell of the SAR, the factory SP-01 mags and the mecgar mags with the rubber base plates lock in easily but the metal base plate original factory 75b mags take a little tap on the base of the mag to get it to seat and lock in. That slight gap that I mentioned of the SAR mag in the CZ is the opposite going the other way obviously. The CZ mags in the SAR must be just an imperceptibly small amount too short and it takes a little bump to seat it. You don’t notice this on the ones with plastic/rubber base plates though because I think you naturally just rack them in a little harder then the steel ones. If that makes sense at all. Hope this helps someone else on the fence of purchasing the gun. I actually really love it and it shoots lights out. I’m glad I took the leap of faith and made the purchase. Now let’s hope the lok grips I ordered fit. They are custom and I’m out almost a hundred bucks if they don’t. I ordered EAA witness small frame long. I know it wouldn’t be the short because that is for the magwell version. I have no idea what the medium would be for but I ordered long because the grip needs to go all the way to the bottom of the grip frame and it made sense to me that they would be the longest version. So here’s to hoping I made the right choice. I’ll share what I learn here when I get them in.