I used a simple cheap CO2 powered airsoft pistol as a base for my carbine project which is still in progress. I reused the M14's inner barrel for this project as well as spare PVC lying around the house. The idea was to increase accuracy of the pistol platform as well as make it into something unique. Project still under construction.
Thank you. I personally think it is sub-par. I only had a foot of PVC, a rotary tool, some drill bits, a chunk of wood and about $50 to use on paint and the airsoft pistol and scraps from my old airsoft project.