Although I 100% understand what youre saying. I'm 20 and cant really afford to purchase 700$ in gun parts and at that point I might as well buy one already completed.
I get it, but there’s no such thing as an inexpensive homebuilt gun. Maybe back in the day when AK kits were <$100 you could say it was cheaper to build, but now I can’t think of a single gun that is significantly cheaper to build than buy. The best way I’ve found to deal with the cost is to buy one piece at a time, as you have the money. Yeah it’s slow, but $700 over 6 months is a lot easier to fit into the budget.
Not sure where they are now, but before the most recent panic, even 80% AR lowers cost more than completely finished lowers.
The only people now who can say “I built a gun and it cost $100” are guys with $5,000+ of machine tools (lathe, mill, etc) and who literally build their gun out of bar stock. And they’re of course not factoring their time into the cost.
“expedient” firearms have their place, but that place is right next to the Liberator pistol. And with the same, very narrow, use case.
I may have missed it, but what’s your goal in all of this? Is it to get a rifle or pistol that you can’t otherwise get? Or is it just to have fun building something?
If you just want to build something, that’s cool. I would strongly advise finding another design to work off of, as opposed to trying to redesign an open bolt SMG. You’re gonna need at least a lathe (and probably a mill) to make the conversion to semi-auto.
If you’re dead set on building something custom, spend a lot of time studying firearm design and construction techniques, with a focus on exactly why things were designed the way they were.