I can't think of the name of it right off hand, but it will come to me, We tried out a couple different ones, at home at the feedlot, using both Vaccines and Antibiotics such as Naxcel. We weren't very impressed with them for a couple reasons. You need to have a "dead on" shot, Nothing even at a slight angle, or we saw the pellets bouncing off the animals. Didn't matter if it was the Vaccine pellets, or antibiotics. You need someone to move the cattle by your along a fence, single file, and SLOWLY to get a quality shot and make it work. Usually the reason we were trying to use it, was because the cattle were so wild, we figured it would be less stress on them, than running throught the chute, but in the end, we had a higher "pull rate" than normal, and picked up a ton of "pellets" off the ground, so we we're impressed at all. We tried different people on the guns, in case of "operator error" and got the same results. When I think of the name of it, I will post.
We've gone to using a Pneu-Dart Rifle for treating "wild ones". Shoots up to 110ft, uses disposable darts, from .5cc to 10cc, and have had EXCELLENT results with it. We've used it for both vaccines, antibiotics, tranquilizers and wormers. We use the pump up style, but C02 riles are also available. Highly Recomended! and run $316.50 for the rifle, No fire-arms license required, ready to use in 3 minutes or less.