As milsurpo surmised, you have a two-band short rifle, most often issued to Sergeants. Not only do they have a somewhat thicker barrel, they have five-groove rifling, and are there held to be more accurate than the three-groove infantry rifle. I have one of each, a three-band and a two-band model, both Canadian and both with military history behind them.
Getting these to shoot is a useful exercise, with everything that you need available from just one source, albeit one situated in Spokane WA. Since I'm a furriner here, I'll let the natives advise you on what you need to know to get shooting.