hell i have been shooting the hell out of some of my ar-15 with the cheap ammo for some years now. can't say i have had many problems even burning the toxic yugo 7.62 brass and 5.45x39.
some of the brand name ar-15s have gas ports a shade too small to run the cheap stuff which has slower lower pressure powder.
the only cheap stuff that wouldn't run in mine was that one batch of tula 55gr that had the bad powder. i mean really bad powder --LOL!
that batch also was not 100% in my ak which would damn near cycle on just a primer--LOL
PS i got a PA optic. it is pretty good , uses three hearing aid batteries and is very bright.
so far it holds zero.
my only gripe so far is it don't have a green cross-hair.
i am thinking of just going with regular 4x scopes just so i won't have to deal with batteries--LOL
Get the smallest red dot you can for best performance and results.
This one isn't really a "Dot " scope per-say but pretty compact and has a fixed recital if your battery fails or when you don,t need the lighted X-hairs/dot. It's a Sig Sauer CQB type scope model CP1 that is red and green lighted and the recitals show when not lighted with a bullet drop markings. There quite compact and light and work real well for two eyes open shooting ,3X magnification and nice clear optics. Had mine for about a year and a half now and it works great and hasn't even eaten a battery yet.They've gone up quite a bit lately in price though and are now about 190, opposed to the 100 I paid for mine when I got it. I've used this one from 20 -150 yards and it works great,some youngster with sharp eyes could probably use it at some pretty respectable ranges I would think,,I bounce beer cans around easy at 150 with no issues at all. I don't have any place to shoot much further than that , but I have shot 2-3 times at crows around 400 or better and just barley missed so with a little long range practice I'm sure I could dial it in pretty easy.
There damn nice though and I like them better sense you have a fixed recital to use for bright conditions that would normally bleach out any other dot sight. That type is better IMO
I have a couple of PA sights. The Mini Red Dot and a Full sized. Both have served me well. (they Get cycled through what ever I am playing with) They Hold a Zero well as noted they have a slightly blue ish cast to them. the Mini which I picked up about 3 months ago even has NV settings.
One of the Nicer Features is the service. If it breaks in the first year send it back and they replace it . Period. As a proviso though , Marshal the owner is VERY clear these are recreational sight , ot recomended for home defense law enforcement or active duty. For My "get serious rifles" I run an Eotech and aimpoints 1 M2 1 PRO and one HI