So, a regular Marui compatible AK magazine won't work with the PTS ACR AK lower? That is really disappointing because I considered one of the greatest strengths of the Masada design to be versatility. However, only being able to use those specific mags is very limiting. Also, the two Beta Project mags I've seen have had 5.56x45 molded on them; which makes me wounder what the point of swapping would be since it would be the same ammunition in RS.