Originally Posted by Danke
It does make a difference. Airsoft pistol mags mimic the fit of the actual pistol so if what you've got is based off a double stack then you need pouches to fit that.
x2 when going rigid. With soft stuff sometimes BFI can kick in and it can be forced. Not always though.
In that case, is my KWA USP Compact based on the 9mm version (which I suspect) or the .45 or .40 ?
Note that in all three cases the overall height and width of the firearm (not the mag) are the same, as per http://hk-usa.com/hk-models/usp-compact/