Yeah I have, mainly did it for the 360 Achievement.
This game was great no doubt but it was riddled with glitches, never has a game frozen so much on me...unfortunetly these problems soured me on buying this otherwise fine game.
There's three level of upgrades for each weapon, including the grenades. You gain upgrades by using the weapon to kill enemies, simple-
M1 Garand Rifle
M1911 Colt.45 Pistol
M12 Combat Shotgun
Thompson Machine Gun
M1918 Browning Automatic Rifle(B.A.R.)
M1903 Springfield Sniper
M18 Recoilles Rifle
MP40
KAR.98
Gewehr Rifle
STG44
Mauser (located in the Varsity mission in the factory with the Rail Gun, it's in the control room upstairs in the safe, you'll have to blow it open)
I believe this is all of them, it's been a litttle while since I played
The thompson is'nt actually a machine gun its an SMG.
U missed out a pistol... theres a german pistol (forgotten the name) on the secind to last mission in a safe
Your not too bright are you, I mentioned the Mauser...