Santa dropped off some nice toys this year (Daniel Defense DDM4 V5, ACOG TA31H-G on a TA51 mount, Troy Front HK Style BUIS, Troy Rear BUIS).

Unfortunately the Troy BUIS combo are back ordered for 1-2 weeks. I want to hit the range tomorrow but didn't want to have to re-zero the ACOG if I have to move it forward on the rail to install the Troy rear BUIS. I need to figure out where the ACOG needs to be mounted...and still leave room for the BUIS. I want to be able to mount it, then index mark it. I know I will have to remove it to zero the BUIS combo.

So....here are a few questions for those running ACOGs on the TA51 mount with a Troy rear BUIS.

1) Does the Troy rear BUIS use only one rail slot?

2) If so, and I install it on the rearmost slot, will it interfere with the charging handle?

3) If the BUIS does use only one rail slot, and I mount it on the rearmost slot, then what rearmost rail slot can I mount the rearmost slot screw of the TA51 ACOG mount? Will they butt up against each other or will I need to leave a single rail slot gap?

4) How many post before I hear "Ditch the ACOG mount and buy a LaRue"?  

Thanks in advance gents....

1) * I dont own that paticular troy buis but if it is anything like my MI it will likely occupy 1 slot  *ill take a picture of mine and post it in a second for clarification*
2) it will probably rest on top of the flat portion before the charging handle, not in the way.
3) personal preference due to eye relief?
4) Buy the LaRue mount!!!!


picture one of the rail.  The threaded screw for the BUIS lands on grove T1


Sight installed and lowered.


Sight installed and raised.


Keep in mind this is with a Midwest industries BUIS but I would suspect the troy to be very similar and possibly a bit lower profile.
Hope this helps

Damn dude... you got hooked up this Christmas.  Did people really get you all of that shit or did you get some of it for yourself?

The Troy BUIS only takes up 1 but the TA51 can't attach properly bumped up on it so you have to give that second rail up as a buffer.  None of that is going to do anything in relation the CH.  And yea, I avoided LaRue for awhile.  Then I bought an ACOG that already had one on it and now I won't use any other mount.  They are 1st class.

I was a very good boy this year. Mrs Claus was very appreciative.

Definitely not avoiding LaRue.....they have seen a couple of $K of my hard earned money. I took a good look at the TA51 mount (which came as part of the package) and after asking a few hard users I decided to use it. If I need to spend the coin on a LaRue I will.

Thanks for the info thornejc...you answered my questions.

ShiftSix...thanks for the pics and info.

Why?