EternalVigilance, what was your AFSC? I got out 4 1/2 years ago. Anyway, there are a couple of reasons why the SPs don't often get recessed rounds. 1. They use ball ammo. It slides up the feed ramp of the barrel without much resistance. If you use hollow points or a .40 S&W which has a flat nose, it won't make as smooth a transition into the barrel. The other reason those guys don't have KBs is that they rarely ever have to shoot their M9 except to qualify and I believe that they are given ammo at the range for that.
Also, I have seen pics of Glock KBs; they actually contain the explosion very well. The gun gets totaled, but I haven't red of any serious injury. I have a G19 and I'm not a big fan of Glock personally, but they are good guns and the KBs are 99% related to ammo malfunctions, not the gun like some Glock bashers would like to tell you.