I'm trying to select the proper A.R.M.S. #40 model for my Bushy M4. I've got an Eotech 511 A.65 mounted directly on the flatop rail and I would like a BUIS that doesn't require replacement of my front A2 sight with a taller version. Do I need the A.R.M.S. #40 Low Profile?

Another option I'm looking at is the RRA dominator. Does the Dominator require a taller front sight?

Thanks in advance for any advice given!!!

I am in the same position you are. I just got a Eotech and want a BUIS. I am looking at the ARMS and I would like to know more about the RRA Dominator mount also. Since I have a RRA rifle I would think that the Dominator would line right up with the front sight. Someone out there should be able to help us.

Quoted: I am in the same position you are. I just got a Eotech and want a BUIS. I am looking at the ARMS and I would like to know more about the RRA Dominator mount also. Since I have a RRA rifle I would think that the Dominator would line right up with the front sight. Someone out there should be able to help us.

I would have to think the EOtech Dominator mount is gonna work on a RRA rifle, since they are the same company.  The ARMS was designed to be used in conjunction with F marked front sight bases, so unless you have one of those or a taller front sight post, it's hit and miss whether your rifle will zero.  My Bushmaster does, but just barely, and in all reality I probably should get the new, taller, front post since it is pretty maxed out where it is.  If you really want the ARMS, go ahead and buy it.  If your front sight doesn't have enough adjustment, a taller front sight post won't cost a lot.  RRA may even give it to you free.  I have heard of people calling Bushmaster and they have sent the new post for free.  Might call them even if it doesn't work out, just say you have a Bushmaster.  

Thanks for the help everyone!

I didn't realize that "Low Profile" (with the A.R.M.S. 40L) meant the sight was more compact when folded. I thought it was related to the height when opened.

I'm going to pick up the A.R.M.S 40L today. The local gunshop has them in stock for $95. It's Saturday morning, so I'll have time to get it mounted and try it out today. If I need a taller front sight for the Bushmaster, no big deal. They are not expensive if I don't score a freebie. I'll let everyone know how it works out later.