I don't know about the rifles, the Sixers seem to have bullets but then the security force had some kind of lasers if that wasn't just an aiming device. But when the dino was heading towards the fence the Colonel said to use the sonics when the heavy machinegun looking things in the guard towers opened fire.One other thing that kinda bugs me-- what's up with the bullets only seeming to sting the dinosaurs? I get that they're huge and have thick skin, but they're not bulletproof.
They shouldn't be any harder to bring down than one of today's rhinos or elephants. Especially with the more powerful weapons they probably have.
I'm under the impression they are using some kind of stun bullets. (is there such a thing?)
It does seem as the weapons brought from the future were meant to deal with men not large animals.