If you're at all into guns, hunting, dinosaurs, and science fiction, know that L. Sprague De Camp wrote your ultimate short story back in 1956. Entitled "A Gun For Dinosaur", it takes the form of a narrative, told by a professional time-travel hunting guide explaining to a potential client why he won't take him back to the Cretaceous in pursuit of a thunder lizard head to mount on his wall.
You see, he refuses to take clients who aren't large enough to handle the ferocious recoil of a .600 Nitro Express double rifle, due to an unfortunate incident involving an earlier client and a .375 Magnum Winchester Model 70, an incident that he goes on to describe in great detail and which is, actually, the meat of the story. No pun intended.
I read the story in a collection of his shorts, The Best of L. Sprague De Camp, and have re-read it literally dozens of times since. It's fun on so many levels, with an interesting viewpoint character, a good feel for hunting and firearms, and a terrifically detailed look at pre-Robert Bakker dinosaur paleontology, with lumbering tail-dragging lizards and aquatic apatosauruses. I'd often wished he'd reused the mileu for other stories in the years since I first read it.
While browsing RobertaX's bookshelves yesterday, imagine how happy I was to find that Jim Baen apparently had the same idea I did. Rivers of Time, published by Baen in the early '90s, contains "A Gun For Dinosaur" as well as eight more stories of Reginald Rivers, time-travelling Aussie and professional hunter extraordinaire and all up to date with the changes that the intervening 30 years between the writing of the original story and the last decade of the 20th Century have wrought on society, hunting, and paleontology. If you are at all interested in dinosaurs, hunting, shooting, or SF, read it. You will not be disappointed.