http://i659.photobucket.com/albums/u...y/IMG_3841.jpg
Aimpoint/Bobro/LaRue. The spacer is Aimpoint.
http://i659.photobucket.com/albums/u...y/IMG_3834.jpg
http://i659.photobucket.com/albums/u...IMG_3843-1.jpg
LaRue Mount
http://i659.photobucket.com/albums/u...y/IMG_3852.jpg
Bobro mount
I ran the Bobro mount at the Magpul carbine class, worked great, no issues.
I ran the LaRue mount at another class, again no issues. When a buddy borrowed my LaRue and used it on a LMT upper, there was a small bit of wiggling.
On the Colt no issues. I like both, Mark and Andrew make very good products. The cost are close. Each have strong/weak points. Both have strong levers to clamp the mount onto M1913 rails. I still run both-tough choice. Good luck.