I'm in Kansas and we don't have any restrictions on them and they're as close to full-auto as you can get without Spending another $200 for a tax stamp and taking months to get your NFA approval. First "Binary Mode" 1 round fires on the trigger pull and 1 round fires as you release the trigger. Both have the functionality to cancel the Binary 2nd shot by moving the selector to safe or semi-auto before releasing the trigger. There are 2 major players and there may be others I'm not aware of. 1. Franklin Armory - their AR trigger will fit all mil-spec receivers, and most all uppers, regardless of the bolt carrier. They also make a binary trigger for the Bushmaster ACR, HK MP5 and HK 91, 93, 94 (basically all 9X rifles), one of the B&T APC 9mm and CZ Scorpion EVO. 2. FosTech Echo - they only have one, which is for the AR - and with it you must use a M16 bolt carrier. It's a bit smoother and has a shorter reset. It's a drop-in design so it's easier to install than the Franklin. Both have a trigger pull that is about 4.5 to 5 pounds and a 3-position selector; Safe, Semi-auto and Binary There are rumors that the Franklin AR trigger is easy to "out-run" and basically that means you end up with a dead trigger, but if it's properly tuned I don't think you can ... the Franklin kit comes with 2 alternate buffer springs and alternate trigger springs ... And the instructions state that your specific gun ay run better with ah H or H2 buffer. The AR is the most finicky. The Echo is completely different from the Franklin design, but Franklin Armory holds an intallectial property patent on the Binary trigger ... So even though it's design is different they have to pay royalties to Franklin Armory. Also, it's design is similar to the Hyper-Fire trigger and they have to pay royalties to Hyper-Fire as well. I've got both AR triggers (Franklin & FosTech) and a Franklin for my HK's ... They are great for double taps or mag dumps if you're in to that. I plan on keeping the Echo mostly for 2 uppers; one in 223/5.56 the other 7.62x39 The Franklin will float around a bit more as I've got uppers in 22LR, 5.7x28, 9mm and an Ares Defense belt fed ... All have non-standard bolt carriers. Remember, a day at the range is better than any day at work!