Get a red dot with an improved reticle rather than a simple dot. For example, the Lucid HD7 has a separate reticle turret with four choices. Besides a dot, there is an EOTech type circle dot, a 25 MOA circle around a 2 MOA dot. It also has an ACOG type chevron calibrated for M193 ammo, and a "T" dot with a horizontal bar (useful to prevent canting) around a series of vertical dots for initial zero and longer range holdover.
The circle dot is very effective for rapid target acquisition. The HD7 is rugged, armored, ACOG size, and usually sells for about $189 or less, shipped. I have run it on a 12 gauge tactical shotgun with full power buckshot and slugs. That recoil does not faze it. The one in the photo is mine. It does have upgraded ADM QD lever mounts and optional Butler Creek lens caps. Lower 1/3 cowitness with your irons.