My experience with the STI 40 (Edge) is that long OAL ammunition is required for reliable feeding. I run 1.175" OAL where as spec for the 40 factory loads is 1.135" max. With proper loads the gun is very reliable. I suspect the compacts from STI would be the same. Obviously the 1911 was designed for the longer 45ACP where as the original idea behind the 40 was a 9mm format gun with big bore punch. BTW, my STI 40 loads will not even fit in some of my Glock 40 mags!