GUN TALK is a good collection, but not common. Aside from my copy I've only seen a couple of others, though no doubt a web-search would turn up a few.
Aside from Les Bowman ("Western Rifles") and Jack O'Connor ("Some Notes on Big Game Cartridges") there are chapters by Charles Askins, Jim Carmichel, Warren Page ("One Man's African Rifles") and Ken Waters. There's also one by my old editor at FIELD & STREAM, Pete Barrett, on shotguns. Pete knew a hell of a lot about sporting arms (he went on as many safaris as O'Connor, back when a typical safari was a month) but unfortunately didn't get to write about them much.
I sure would like to have that 5 1/2 pound Beretta Barrett owned!
