I guess we discussed it in another thread.... so I'll say it again, though you should search around and find out for yourself...
Yes, the Primary fire of the Shield Gun was directly inspired by the Impact hammer. You charge it, and release, sooner for less damage/height, later for more damage/height in jumps, and running with a full charge will autodischarge the hammer if it touches a player pawn, or pretty much anything that can take damage.
The IH in UT though was much more accurate in doing so. I hope that returns as well.