Sig makes one I really really like. It's not a dot but a normal BDC X hair arraignment with red and green illumination,,I like it very very much I think it's called a CP1. It's in the Sig sites accessory section.
It's one of the clearest scopes I've used for both eye open shooting and beer cans at 100 yards is a snap with it so you can still get some good precession shooting in with it , unlike many of the 2-3 moa dot scopes I've used. Seriously, try one if you're looking for a 3X type scope,I doubt you'd be disappointed in it. Ive had this one for 2 years or better on my M4 Sig and it gets used fairly frequently and the more I use it ,,the more I like it. It's never lost zero nor have I had to change out the battery yet either.
There's others out there that are similar, but many I see are much higher priced than the Sig's and not as good IMO. One of my buds has a Bushnell one that is similar to it and he likes his, I've never used it but he swears by his and there about the same price,,150-175 ish depending where you get it.
That would be my recommendations on one, but can't honestly vouch for the Bushnell one, just going by what a Bud told me. But he's been an avid shooter/ hunter for many years and knows his stuff and he says good things about his so I doubt he'd steer me wrong.