[@Clockwork giant] Yes, the homemade weapons wont be just pipe weapons. Some will be made of PCP pipes, things from other guns, or even built from hollow shell casings. They wont have a 'Base reciever' just a fully custom reicever. 

Here

[img]http://2.bp.blogspot.com/_-zlIBgJxnuk/TTjj-KXOmwI/AAAAAAAAAKk/zbTRJwDismI/s1600/800px-1-weapon_tihar.jpg[/img]

A homemade Pneumatic 15mm Sniper rifle built by a more dedicated raider