i did a little reseach that was out side of the game (about WWII guns)
the springfield is a bolt-action rifle
the M1 grand is a very accurate gun but only hold 5 rounds
the M1 carbine is a accurate gun but with little stoping power cause it uses a pistol round
the tommy gun is a good gun accurate high stopping power.
the bar is a high RPM good but very inaccurate but very hight stopping power
the grease gun is a SMG it use pistol rounds like the M1 carbine but is lest accurate