[Little Ray]

The easiest sort of firearm to construct is an open-bolt submachine gun like the Sten or M3A1 Grease Gun.
Just sayin’.

[Who is John Galt?]

The easiest sort of firearm to construct is an open-bolt submachine gun like the Sten or M3A1 Grease Gun. Just sayin’.

That may well be true, if you're referring to setting up a production line for military-type weapons. For an individual putting together a single firearm for personal use, a single-shot smoothbore (for low pressure shotgun or handgun ammunition) is probably the "easiest sort of firearm to construct," using commonly available plumbing supplies...

;^)

[archy]

The easiest sort of firearm to construct is an open-bolt submachine gun like the Sten or M3A1 Grease Gun. Just sayin’.

The MkII Sten is a little easier because it uses a receiver of simple tubing, basically a pipe. The later MkIII Sten and Grease Gun use stamped receivers requiring a stamping press and welding equipment to join them.

But there are a number of other designs using a tubing receiver that take only a few hours to throw together, the Vietnam favorite Karl Gustav M45b *Swedish K* and the Czech M24/M24/M26 *Czech Uzi* series among them. Get one for a sample and a couple dozen copies are easy, as numerous biker gangs have found out.

https://sofrep.com/specialoperations/swedish-k-unsung-friend-american-special-forces-vietnam/