Those are some damn good points. One of the few things I can think of for this would be some sort of blowback system specifically for the bolt. It would probably be way too complicated to be feasible to do though.
That's more or less exactly what I was thinking. Take some ideas from the Magstrike and implement them in the Longshot. The magazine system might still be used, but I can't see the bolt system being used. As for the time it would take to load and pump and such, it might be around the same time to prep a Magstrike. Considering you have to do basically the same things, load a clip and pump. I was planning on working on something like this over the summer, since it always gets boring when one doesn't work.