Best I've found - search Wera tools. They make great screwdriver bits and sets of all kinds. The bits are hollow ground to fit correctly in slotted screws commonly used in gun assembly. They ain't cheap though. They also sell an excellent torque screwdriver.
I dont know what you are using but I have a set of Grace Screwdrivers from Cabelas and they work great. I normaly dont tighten screws tight enough to break or bend tips though.
I bought a couple of the Pachmayr 31 piece sets for about 15 bucks each on sale a couple years ago. I keep one at home and one in my field kit. They work great. Phillips, flat, star and allen, all included. Nice little set.