If by "MSHP" you mean The Mississippi Highway Patrol, your G22 should be a 3rd Gen., as MHP only adopted .40 cal. Glocks in 2004. It is my understanding the patrol recently switched form .40 to .357 Glocks.I'm not sure what happened to the .40 cal. guns, but they could be out there.
As to the polished slide, I've never seen a Trooper with a polished gun.
Hope this helps. Maybe someone more knowledgable that me will chime in.