It is legal in Texas and Oklahoma, but I am not going to look up all 50 states and list them. Contact you local AG office or BATF office for restrictions in your state. For ammo selection, a clean burning sub-sonic is best, like a factory 230gr FMJ. Dirty reloads will gum one up in a hurry. The H&K supressor is made by Reed Knight at Knights Armaments in Vero Beach, Fl., but any quality suppressor from Gemtech, AWC, or Wilcox should work quite well.