"Designed by Ken Warner and Pete Dickey; this rare knife was made during the late 1960s and early 1970s. Only a few thousand were made by Hackman with a 1/4 inch blade in Finland, with the majority produced by Garcia in Brazil with a 3/16 inch blade. The Hackman survival knife was intended for private sale to military personnel bound for Vietnam. The Randall Model 18 had made the hollow handle saw back popular with the troops, but Randall could not keep up with demand. Like the Randall this knife featured a watertight hollow handle and a massive 1/4" thick stainless steel blade.
From Ken Warner's book The Practical Book of Knives circa 1975, Chapter 7-The Sharp Pry Bar: I was responsible for the shape and the grind of the blade and the overall configuration. My collaborator, Pete Dickey, figured out the rest of it. In essence, it has a hollow stainless steel handle, closed watertight by a large threaded pommel. The space inside is nearly the size of two 12 gauge shotshells, which means it will hold matches, pills, another little knife, hooks and line-a whole raft of stuff that could come in handy. Pete went ahead and had packed a miniature kit that went into the sheath's pocket and had a lot of that gear in it.
Anyways, I put all I could think of into that knife to make it do as many jobs possible for a fellow who, all of a sudden, has to do it all with a knife. So did Pete. It is heavy and tough enough to chop wood or meat or bone. It is wide enough to dig with if you need a hole in a hurry. The saw edge is designed to get its users poles without making loud noises. Its steel won't rust, and it's hard, so it hold an edge. If you had to hurt someone with it, it is equal to that job. It will slice very nicely and is, after you get used to it, pretty handy for dressing out game. It has a couple of holes in the modest double guard, and by lashing through those to a pole seated in the hollow handle, a rather impressive spear results".