Kind of a newbie to the world of handguns. Have hunted for years and own numerous rifles and shotguns, but just recently bought a Subcompact Springfield XD 9mm. I was talking to a friend of mine at the range today who shoots a Glock. He was telling me that for the Glocks they have interchangeable barrels, whereas I could put a .40 barrel in a 9mm frame. Is this possible with the handgun I have? Could I buy a .40 or .45 barrel and switch it out with my 9mm barrel? Is this legal? My friend said after speaking with a seller at a local gun store, who had spoke to Pennsylvania State Police about the issue, that this is still legal and somehow the serial numbers can still match. Has anyone done this or does anyone have further information on the issue? Thanks in advance!