Exactly right! Unless you are a Fed agent and want to have some bogus charge on a guy trying to sell a shotgun. That is what happened to Weaver. He cut off the barrel where the "buyer" said to.
The point is that these guys probably weren't trying to sell pipe bombs. My guess is that this is another case of entrapment.
Randy supposedly cut the barrels to 18". Someone else shortened the stocks... Instant Felony for Randy.
I'm betting on Tannerite. You can make it home with an old blender and powders you can buy off ebay. Looks impressive on film and the general public won't know the difference.