Yes there seems to be a glitch when you dashboard and start the game later on your class with the peacekeeper is reset igs annoying but only happens when you dashboard and play later on
It's got something going on without dashboarding too. I respawned with a knife in my hands, when I tried switching to the Peacekeeper I had no gun. The CAC was empty. Then when the game ended I found the original default gun (a shotgun) was now in the slot.
The peacekeeper wasn't even on the list of available guns at that point. I restarted my 360 and it was back in the list of available weapons for the CAC. I only had time for a few more games before my morning appointment, but it seemed to work fine after that.
As I mentioned before, you don't even have to leave the game for it to happen. I had the gun disappear during a respawn. After my earlier post I went back and played a few games. It happened again between games inside the same lobby.