FWIW, the 10-round mag that came with my FCP-SR doesn't work well in that gun, either. It constantly mis-feeds, or the rounds jump out on their own. Some people have had luck stretching the springs.
I never try more than 5 rounds (I'm usually shooting 5-round groups).
If I had known then what I know now, then I probably would've paid extra to buy a rifle that feeds from AI/MagPul mags.
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