A few years ago I did a video on bump firing, bump firing is a technique that, if practiced, can allow a semi-automatic firearm to simulate fully automatic firing. This is done without any modification to the firearm, and is legal in the united states.
Without acting like a lawyer, the basic premise is as long as a single manipulation of the trigger fires a single round and it is your finger that activates the trigger then Federally, there is nothing illegal happening.
Bump firing is cool, and it is good legal fun for many, but it takes practice and is not effective for actual use.
Of course, it is my opinion that the Second Amendment applies to common military arms up to and including warships and artillery, I am not willing to risk my status as a non-felon to own an illegal automatic weapon and my wallet does not support the purchase of a legal one.
That is where the slide fire stock comes in,SlideFire products turns semi-automatic guns into a rapid fire gun. As of the time of this post, slide fire stocks are not federally regulated, and do not change the legal status of a semi-automatic rifle.
That may change in the future, so if you are interested you should probably go ahead and purchase one.
While I do not find these to be effective for normal self-defense use, I think they are really cool, and may have a place in a prepper arms room. I support all moral ownership of all types of firearms, because its your right to keep and carry weapons in this county. In order to support this right, I am sharing a 5% off coupon for SlideFire Products: Save 5% sitewide on SlideFire bump fire stocks and parts. Use Code RAPIDFIRE. Coupon Code: RAPIDFIRE