I have a Bushmaster 16" with the removable carry handle.  Does it make any differnce which ACOG I get, the TA31 or the TA31F?  Is the only differnce that one comes with the mount and the other one doesn't or are there other differences.  Can you get any reticle in either one? Which mount would be best if I want to get it just high enough to get over the front site?  Will this require a change in cheek weld?  I know I'm asking a lot of questions, but I want to do this right the first time!  Thanks.....

I posted the same question 2 hours ago... [url]http://www.ar15.com/forums/topic.html?b=3&f=18&t=166575[/url]

Okay, the TA31f is build with a flat top M4 in mind, the TA31a or the TA31 is build with carrying handle 20inch.  if you mount the TA31 on a flat top, you will have some different POI then the BDC in you reticle would suggest.  it really isn't that big of a deal.  I use a TA31a on a 18inch flat top and regularly shoot past 300 plus meter in 3gun matches.  

TA31 is donut, TA31a is triangle, and TA31f is chervon.  I dislike the chervon the most since it is too fine to stand out when your are using the BAC feature for fast traget acquisition, you just don't pick up the the reticle fast enough.  the chervon is great for mid top long range shot.  

Hope this help.