Sorry, just couldn't look it (your exact rifle) up at work, so I was guessing based on the ES2 part of the name, I have a XM15E2 that is a A2 style upper receiver.... see assumption gets me in trouble again :roll:

hmm.. tons of options and I think that something like the Super Sniper 10x, Burris 3200 Elite 10x fits the bill IMHO.. Nikon, Bushnell or Berska (SP?) - not a customer so I don't know models - are others positive comments about.

I use a 3200 Elite on my 20" AR and it's a solid optic. I pulled if off of my Remmy 700 and replaced that with a SS 16x. Both are around 300 w/out rings.

I really didn't mean to sound critical about the funding range..

You can always shop around a few places, here are a few that I check when shopping...

www.swfa.com

www.snipershide.com - forums - I bought both the SS and Burris there.

www.opticsplanet.com

www.midwayusa.com
Hope that helps