The M1 Garand.

[Larryjk]

There are many instances of the GI's knowing the Japanese and German soldiers listening for the ping and charging after they heard it, thinking the GI's rifles were empty. The GI's would have one guy fake the sound and then they shot the charging enemy. Pretty sneaky - but effective.
I also have a couple Springfields (03 and 03-A3) and the little M1 Carbine. I would like to have an M1A, but don't want to sell the farm to buy one.