When you press T or G you change de Weapons Category...but it´s shown in portuguese..sorry for that!!

But each number in the keyboard is a different gun on the selected category...
The M1 Garand is inside the "carabina" category...then press number 2 to use it.
The grenade is available in the number 0 in these categories: "carabina"-carbines "metralhadora"-machineguns "Sniper"-well..sniper!

There is 40 weapons in the game... just change the category and press all numbers..then change again and press all numbers...there you will see them all!