If you're worried about an end of time scenario look at an Aimpoint CompM4 or Micro because battery life is measured in years and not hours. EOTechs and others in the Aimpoint line up are great but battery life isn't as great, and in terms of the 3v battery versions isn't bad but not great, comparitively. Both options will accept a magnifier but if you're sticking to 300m and under maybe the extra weight of a magnifier isn't worth the benefit.
Another option, given the same scenario, would be something like a Trijicon Reflex or tri-power since neither really requires batteries (tri-power does take batteries if you want to crank up the illume but is a fiber optic type sight). The ACOG would be another good choice but you can also drop the VLTOR stock and go to a CTR with a cheek riser to mitigate the cheek weld concern. A TA31F or any of the BAC style sights would be best so you can use the fiber optic aim point as a CQB set up.