You have likely heard of the SIRT training pistols, but did you know that they came out with a drop in SIRT conversion for ARs?
http://nextleveltraining.com/arThis is a bolt that drops into your upper receiver, and when the trigger is pulled, if fires a laser. It is functionally correct with your safety selector, and makes it so you do not have to charge the bolt after every pull of the trigger.
Your first question is: how does it reset the trigger? Quite simply: it doesn't. It instead keeps the hammer charged and operates from movement of the trigger bar alone. There is some fiddling required to get this set up the first time, and the pull weight is set at approximately 6 lbs. Once you get the hang of it, it only takes a few seconds to install or remove.
"Enhanced Dry Fire Training" <the best description I have heard.This is an excellent tool that can significantly enhance your dry firing sessions. It can give you solid feedback on what is really happening with the fundamentals. It can be useful for both support and standoff barricade drills, target transitions, support side transitions, weapon transitions, position transitions, force on force, and several other things I did not think of for this post.
What is this not good for? Not for mag change, immediate, or remedial action drills, since the bolt cannot be manipulated in any way. It is pointless for recoil management, and to a certain extent does impose some training gap in other areas, comparative to live fire (it does not matter what you do, there is ALWAYS at least some training gap when compared to real world kinetic engagements). Still it is a great tool when used as intended.
Red laser model:$150 MSRP (I've seen it for $125 on ebay)
(+) works with laserlyte targets systems
(-) it can be difficult to tell what is going on in front of red dot or holographic optics
Green laser model:$250 MSRP (I've seen it for $225 on ebay)
(+) increased visibility over longer distances and in daylight
(+) less likely to wash out when using red dot or holographic optics
(-) a hundred bucks more?
*NLT provides wholesale pricing for Instructors, LE, and Military.
http://www.youtube.com/embed/0I-kFrvJ4O8 Side Note: I have an extra one of these (green laser model) hanging around. I was thinking about raffling it off with proceeds going to the NFOA-PAF. Not sure there is the demand for it. I may just hold onto it and offer it for sale at my classes, not sure.