"Slide fire" is a dedicated bump fire stock for ARs. The rifle is free to move fore and aft in it. There's a fixed shelf on the left side for the tip of the trigger finger. With a loaded weapon- put finger on trigger shelf and then pull forward with the support hand. Rifle fires, recoils rearward, allowing trigger reset, and the support hand pulls the rifle back forward naturally. As long as the finger stays on the shelf and the support hand pulls forward the rifle will continue to fire.
Do a Yputube search on "slide fire" I reckon you'll find video of Bubba and his friends...
ACOG: The optic that is bad news for folk going against US military small arms fire. Anvil tough. Super clear. Fiber optic AND Tritium reticule illumination.
TA31RCOM150 (4x calibrated for M4s)
TA31RCOA4 (4x calibrated for the 20" M16a4)
TA648 (6x for 7,62x51 GPMGs and the current BritishDMR, the L129a1.)
Etc., etc. And they work well close in, too if the operator keeps both eyes open. The arrowhead superimposed close enough to work as an "OEG" occluded eye gunsight).
Sorry for the fuzzy photos. Haven't mastered doing pictures through a scope.