hello.
i use wilson ten round .38super mags in my sti single stack for idpa "esp" division.
i put through 1,200 rounds last week through the gun and magazine combination.
couple problem areas. wilson recommends running rounds on overall length between 1.240 and 1.260. i loaded factory winchester silvertips as a carry round. it is well over 1.260 and the front of the bullet binds on the inside front of the mag body after about the fifth, or sixth round is inserted. it makes getting that tenth round in the mag right next to impossible (i finally did it and dented the case of the 9th round). on top of that, from the sixth to 10 round the tip of the round stays nose down in the magazine and causes "hang-ups" on the feed ramp. it was not as hard with my reloads at 1.250 length.
another thing. with ten rounds in the gun and one in the chamber. if you are running light loads (power factor 135, or under) the slide/recoil spring combo is slowed down considerably by the upward force generated by having ten rounds crammed in that magazine. it caused me malfunctions. either cut a coil off, or download by one round to nine in the mag and one in the gun.
loading 10 rounds in those magazines is very hard. once you load them, leave them fully loaded for at least two days to let the spring get its "set".
i am going to metalform magazines. much better all the way around. if you want to buy my mags e-mail me at
[email protected]
hope this helps.