I have a PneuDart. Bought it through my Veterinarian. It's a pump. I've been happy with it and it's had a workout this summer. I think every animal I own has had pinkeye at least twice.
If you get one, make sure you go through PneuDart's website with a fine tooth comb. There's a lot of good information on it that will save you grief and $$$. Sign up for and read the eBook entitled Shooting the Bull.
The PneuDart darts are single use. I like not having to buy .22 blanks or Co2.
My cows react harder to the dart than calves do. Calves will make a loop and go right back into the cows and it's over. The cows bawl, jump around and get the others worried.
Number of pumps on the rifle are determined by the size of the dart. Draxxin is all I have used in my darts. 10cc is as big of a dart as they make. Aluminum body-you can't see the contents. I have had 3-4 bounce off the intended animal which I didn't appreciate and I don't have an answer as to why it happened.