Looking for one to go on my Block II Colt. Not concerned with being clone correct, this is just my go-to rifle. I can get the Eotech for about $400 less too. I’m not super knowledgeable on the two. I have only used a laser once since getting out of the military but I want a visible laser with plans of night vision early next year. The fact I can get the Eotech for under a grand is very appealing but I’m more concerned with the better quality.

There aren’t too many differences functionally.  They both have generally weak IR illuminators (although the A3 beam can be focused, a feature that’s locked out on the PEQ-15C), IR lasers are on the weaker side, but not horrible, and the vis lasers are comparable to just about any other vis laser on the market.  A3 is green, PEQ-15C only with red.  Neither are useful in brightly lit conditions beyond 10-15y, although the green A3 does seem a bit better.

Obviously the A3 has an all aluminum body, PEQ is polymer.  Both utilize a single CR123.  A3 comes with a QD lever Mount, PEQ is a standard flathead screw mount.  A3 sits a bit taller than the PEQ.  There have been reports of the A3 draining batteries with the switch in the off position, but that seems to have largely been fixed.

If it were my money and those were my only two options, I’d go PEQ.  I like the controls better, performance is very similar between the models, and I have more trust in it’s durability (even though neither are absolutely bulletproof).  Factor in that you can get the PEQ for less than $1k and presumably the A3 is going to be $1.2k-$1.3k and I think the choice is pretty easy.

The illuminator on either of those is going to suck eggs past 75 yards in urban lighting. Indoors or areas where there is little moon/star/light pollution may get you to 150 maybe. If you want to see past 500 yards "and you do want to be able to see past 500 yards" buy either a MAWL C1+, a Steiner D2 or A4.