I'm just kind of confused by the bump stock thing anyway, although I admit I'm not a gun connoisseur. Why do you need to make your gun shoot like an automatic anyway? I'm just legit curious and not attacking the gun lovers. Personally I'd love to learn marksmanship but kind of lazy and don't want to jump through the hoops where I live to do so.
My personal opinion is that the bump fire stocks are stupid gimmicks. I don't have one and I don't want one. To function they have to be held loosely so the recoil of the rifle slides the stock over the spring, which kind of bounces the trigger against your finger. Any kind of accuracy beyond 20 or 30 yards is out the window.
Shooting a machine gun has some novelty to it. Every few years for one reason or another I get the chance to shoot some of the military's machine guns, and it's fun. If the registry hadn't been closed in 1986, I'd pay for the tax stamp to legally modify a semi-auto AR into a machinegun, just because. To be honest though ... it wouldn't get much use. There's just only so many times you can dump $10 of ammo into a dirt berm in 3 seconds before the novelty fades and you wonder why you're wasting ammo, missing the target, and dirtying up a gun you'll need to clean later.
In a sense, the existence of bump fire stocks can be laid at the feet of the 1986 Hughes amendment, which was passed by voice vote in a very underhand way (on review it looks like they didn't actually have the votes to pass it). If the MG registry wasn't closed, the market for pre-1986 legally transferrable machine guns wouldn't be artificially inflated to prices that start above $25,000 for AR15 receivers / drop-in sears. These stocks actually cost more than the federal tax stamp to legally transfer a machine gun. The only reason people buy them is because they can't afford the real thing.
(In the same vein, Sig sells a "
wrist brace not-a-stock" that fits on AR pistols. It looks like a rifle stock. People use it like a rifle stock. But ATF ruled that it's not a rifle stock. Using it doesn't turn an AR pistol into a NFA-regulated AR short-barreled rifle ... the same way the ATF ruled that bump-fire stocks don't turn semi-auto rifles into machineguns. Write stupid laws ... people find stupid loopholes.)
I've posted this here before, and I won't digress
too much, but the only purpose of the NFA registry is to inflate the cost of certain guns, to make it difficult or impossible for non-wealthy yet law-abiding citizens to buy them. The NFA didn't ban anything, it just priced poor people out of the market by imposing an enormous tax: $200 tax in 1934 was the equivalent of something like $3000 today. It's just Exhibit #173 in the pile of evidence showing that gun control in the US has its roots in racism and classism. Anyway, I digress.
To answer your question - to take a semi-automatic AR15 rifle and modify it be a machine gun (fires repeatedly with one press of the trigger), a few parts need to be swapped out, and the lower receiver
may require some simple machine work. The parts are readily available for purchase online, as there are 600,000+ legally registered machine guns in this country that occasionally need replacement parts. Possession of all the parts to make a machine gun, when you don't have a tax stamp for a pre-1986 registered machine gun receiver, is a felony that carries a very long prison term.
For now I've just got a basic 10/22 for low recoil shorter range practice. It's OK.
