Since several people seem interested, here's another Flicker set of action series pb covers.
Some of you who read the comments might have doubted Jeff Meyerson's memory of Pepperoni Hero. Doubt no more. Actually, this is an interesting and well-done series, a Travis McGee pastiche. There were at least three of them, all well worth looking for.
Warren Murphy's "Digger" series is a heck of a lot of fun, and Trace is just Digger with a different name. Murphy was, of course, half of the team that created the Destroyer series. The first book wasn't much, but the series subsequently went on to become one of the best of the bunch. My favorite, however, is Murphy's Razoni & Jackson series. The makers of Lethal Weapon liked it even more than I did.
I included three books that Steve Mertz and I had a hand in. Couldn't resist.
I also couldn't resist including some John Whitlatch covers, just because I like them. You can see, however, that they sadly degenerated before Whitlatch's career ended.
The Executioner is sort of the granddaddy of them all. The cover art wasn't so hot to begin with, but it improved. I threw in one of the "Jim Peterson" covers just for fun. That was the name used on the books during a contract dispute when Pendleton wasn't doing them.
Finally, I'm pretty sure "Robert Novak" is Nelson DeMille, but I'm too lazy to check.