Has anyone installed one of these on their AR carbine?  Thoughts, opinions, likes, dislikes?  I will either go with the ARMS #39 gooseneck or one of these on a 9mm carbine.  Thanks for any input.

I installed one on my Bushmaster 16" HBAR, Aimpoint M2 in #22M68.   It went on easy, but the handguard cap was rubbing on the front section of the SIR.  Fixed it with a hammer and punch.  Not the best way to fix the problem, but it works.  I guess you could call it a field installation.  I used to use the #39A2 with my aimpoint, but I really like the #51.   Just more room to put stuff on my rifle to make it heavier.  

I also had a problem with my #51, it would go to the right when I tightened the forward carry handle crossbar.

I ended up relieving the inner edge of the left front and slightly bending in the left edge of the handguard cap.  Here's a view looking down at the top, it's the left side:



And looking up at the bottom, it's the right side:



It's now solid and works great.


Chris

Thanks for the input guys.  And "Chris", thanks for the pics that made your minor modification/adjustments so perfectly clear!