well I bought 2 pro mag magazines for my sig p229 and when I tried them out they both has the same malfunction the 1st 3 rounds loaded and fired with no issues the next 3 failed to feed and the last 6 (in the mag worked just fine I duplicated this 4 times with each magazine (both factory loads and my reloads) I took the "guts" out of a sig mag and installed it in the pro mag body with the same results installed Pro mag "guts" in the sig body and it works like a champ I am at a loss as to what the cause could be. what has me bewildered is that it only fails (and always fails) on the same 3 rounds in the magazine