[KMKeller]

Has anyone here ever used a Bushnell Holosight on an AR with an A2 upper? I'm curious to know if there are any issues with the sight being so far above the bore.

[Steve Smith]

IMHO its a lot better to get the gooseneck adapter and mount the sight in front of the carry handle.

[375nm]

I tried my Eotech 552 Holosight both on top of the carry handle and over the handguards using an ARMS #39 A2 Plus mount.

I'd recommend getting it as close to the height of the regular sights (2.6", IIRC) as possible to minimize deviation from zero at various distances. As the Eotech (and Bushnell) Holosights are pretty high already, the only way to do this is to mount over the handguards (or on a flattop.)

It wasn't unusable perched up there on the carry handle (and would probably be OK for indoor/house distances), but I didn't like it for 50-100yd stuff.

If these online ballistic calculators are reasonably accurate, you'd be looking at raising POI 3.5" to 10" at 50 and 100yds, respectively (25yd zero.) I would have guessed 2-6" from my limited range experience with this configuration, so YMMV.

[KMKeller]

Steve, would something like this:
Bennie Cooley co-witnessing mount (http://www.bushmaster.com/shopping/scopes/eot-12.asp) be what I need?

[Steve Smith]

There are many versions, and yes that is one of them. I'd say shop around a little.

[CWL]

Yeah, get that one, the ARMS I use on my M4gery doesn't allow me to co-witness my holoscope with my A2 sights.

My ARMS does give benefit of closer alignment with bore and decreasing profile, but I have to use the QD if the battery dies.

That Bennie-cooley will let you sight thru an inoperative holoscope. Better design.