Even I, not closely tied to anyone who shots animals...can't buy that one!
Anymore than I can buy that jeeps and HMMWV were designed (although adapted would be the better word) to kill. These are vehicles designed to move people or goods from place to place - albeit those people may be involved in killing other people. Tanks are vehicles designed to kill people. (I know this because, during WWII, my dad was involved in designing and testing tanks.) Perhaps your brother has confused them.
Although I have had a bit of fun with the visual of a jeep being used to kill the enemy. I imagine folks at Camp Pendleton practicing killing people with jeeps. Very fun. Silly, but fun!