Weak feed lips - ProMag Sig Sauer P225 / P6 9mm 8 Round Pistol Magazine

I picked up 5 of these to supplement my factory magazines and they simply don't work when fully loaded. When fully loaded the feed lips are not strong enough and they spread apart letting the round go vertical in the chamber instead of horizontal causing a jam. This is the case with all 5 that I have. I still use them for reload drills but only put 3-4 rounds in them and they are decently reliable then.