Here is a project I finished up about a week ago. Its a singled "sniper" bolt-action Longshot.
Yes, singled blasters arnt very practical for HvZ, but this thing is still alot of fun to play around with!
Although singling the Longshot removes the ability to use a clip, it also makes it possible to operate the blaster without the bolt sled, which is the most common failure point. Due to this fact, I opted to put in the 8kg (I believe) Orange Mod Works spring inside this bad boy and dont have to worry about it breaking.
This blaster is singled with a CPVC and has a 12in barrel, which aside from extending out the front and looking sweet also adds range. Other mods internally include a reinforced trigger to remove any slop, FBR sound reduction (but it is still pretty loud), locked and extended stock, and hot glue filled handle to reduce flex.
Cosmetically I filled the original priming slot and the mag release with Bondo for a smooth finish, followed by a grey w/ charcoal grey splatter vinyl dye paint job and black accent paint.
More pictures can be see here:http://s20.photobucket.com/user/jordanab9/library/Nerf?sort=3&page=1