Amen to that last sentence; those guys would know.
Regarding reliability with 30 round mags...replace the magazine catch with an M2 catch...problem solved.
PRVI Partisan soft point ammo is excellent, with consistent accuracy and excellent terminal performance. Agree with replacing the magazine catch which has an extra shoulder to hold the 30 round mags in place during recoil. Keep the extractor clean and lubed before you go complaining about aftermarket mags (been there done that.)