idpa is not concentrated around 1911s you can shoot whatevers comfortable to you as long as it fits in a class.
The firearms are grouped into five (5) divisions: 1) Custom Defensive Pistol (.45ACP semi-automatics only); 2) Enhanced Service Pistol (9mm (9x19) or larger caliber semi-automatics); 3) Stock Service Pistol (9mm (9x19) or larger caliber double action, double action only, or safe action semi-automatics); 4) Enhanced Service Revolver (.38 caliber or larger double action revolvers); and 5) Stock Service Revolver (.38 caliber or larger double action revolvers). See Appendix One – Equipment for delineations in the revolver divisions. Shooters are then classed by like-skill levels with progression from Novice (NV); to Marksman (MM); to Sharpshooter (SS); to Expert (EX); and, finally, to Master (MA).