Just how difficult is it to manufacture automatic weaponry from scratch?

[Mazryonh]

Originally Posted by MT2008

True, and there are already a zillion books that you can get at American gun shows or even off Amazon that provide instructions for building cheap, stamped sheet-metal SMGs with open-bolt actions.

If the knowledge is really widespread, then why hasn't someone tried to manufacture the "AK-47" of SMGs ideal to the purposes of criminal/terrorist groups? Something cheap and easy to clandestinely manufacture and easily rechambered to fit local ammunition (as well as easily concealable) would be well suited for them, especially if arms traffickers prove unreliable.

While I will admit that accurate semiautomatic fire is best used with rifles, SMGs have nearly always included fully-automatic fire capability for CQB purposes. Fully-automatic weaponry really excels if you're trying to pull a Baruch Goldstein or a Hotel Mumbai as well. Being under fully automatic fire you can't really escape or hide from is uniquely terrifying to people who haven't been trained to keep their cool in such a situation.