Nice guide man, only thing is... There is no mission where you start with a sidearm/pistol. I only found one in the entire game to pick up at one point and I don't remember where, it's the last achievement I need.
EDIT: Ok, so in the level you mentioned, Captain Blazer's Scouts, if you move forward ~20 feet there's an enemy body leaning against some boxes, right next to him is a Colt Revolver. Took 1.5 plays of this level to get the achievement. There's enough ammo in the level to use just the pistol the whole time, and a few grenades to clear out groups.
Last edited by DemonI81; 05-23-2009 at 08:12 PM.