What is the one thing you could not live without on your AR? Could be your optic, stock, grip...but only one! What is your reason?
Eotech or similar holo sight Forgot to list the reason... fast target acquisition.. oh, and a tip off 3 x magnifier with it of course
+1 on DieselScout's post, and to go with that, lots and lots of mags, Pmags specifically. For me it would be a high quality optic. I have a Nikon 2-8x 223 scope. Kind of wish I had gotten something with high power magnification, but I sure can't fault the quality of the glass.
Assuming ammo and mags are not accessories, my two stage trigger is simply the best modification part I have ever installed. Clean, repeatable, light break every time. It was an instant improvement in accuracy, offhand or bench, and thus boosted my confidence with my rifle. I kinda cringe now when I have to pull a stock crispety-crunchity trigger.
I would have to say my streamlight tlr1. Turns any night into day. Having said that, that's the only accessory on my ar!
Optic, or Red Dot. Anything with a single object sighting plane. My eyes are getting too old for irons.
I would have to go with a red dot optic as well. Wish I could afford a super nice one, but I have a hard time putting a 500-700 optic on a 500-700 rifle. The cheap ones the wife and I have work fine for us.
My Aimpoint Comp ML3 red dot. Love that thing I won't say I can't live without it, but my second most favorite AR accessory is my LULA AR15 mag loader. It makes loading mags a breeze and is definitely a thumb saver for long range sessions.
Suppressor, because when SHTF I will still be able to hear you sneaking up on me. That bottle opener is pretty neat though. wg