Here's an old side-cocking Kingman Spyder Classic with an actual H&K 91/G3 Thumbhole stock, 16" CMI Tru-Flight Barrel, 32 Degrees Vertical ASA, Simmons 3x9x50 Rifle Scope, and 47mm Walther Red Dot. This thing is fun to play with and really intimidates newbies in the woods.
Mainly done just for fun. Making an actual assault rifle stock fit a paintball marker wasn't that difficult. This thing really irritates speedballers, which is part of the fun.