I have a MSA adapter which I took by a machine shop to have installed (I posses neither the tools nor the skills needed). After 4 weeks, he finally got it to where it fits extremely tightly. I am sure it will loosen up over time. The magpul seats, but only after a firm smack. He also had to trim the magazine to get it to fit
The main issue, however, is the feeding. I do not have a bullet guide because I've only used the Saiga mag. When I hand rack, it feeds from the right side of the magazine fine but, does not feed from the left. It jams up against the breech, just below the barrel op