I also use the large Wheeler engineering set and always have a bit that fits the screw perfectly. I would highly recommend it.
Right now GBO Sponsor Midsouth Shooters Supply has the Wheeler set on sale at $78.46. Here is the link:
http://www.midsouthshooterssupply.com/item.asp?sku=094-562194&fromsearch=yesThe Professional Set contains: Hinged storage box, 2 ergonomic handles, 3" shaft extension, Hex to square drive adapter, 54 flat bits, 8 allen bits, 4 phillips bits, 3 Torx bits, 15 speciality bits and Accessory tools for Colt, Remington, Smith & Wesson, Mauser, Glock, Garand, Ruger, and more!