Trijicon has 2 scope mount adapters TA51 and TA51W; which is needed for a TA11 onto a Bushmaster Flat-Top? What IS the difference?  Thanks in advance!

The TA51W is for a Weaver rail. You would use a standard TA51 on your Bushy.

Most of the ACOG gurus here suggest that instead of the TA51 mount you use an ARMs #19s that has a quick release throw lever. Use the TA51 if you prefer thumbscrews to a lever.

Good luck with your new ACOG and welcome to the board [:)]

Edit for pics

ARMS #19s:
[img]http://www.adcofirearms.com/acc/acimages/19S-ACOG.jpg[/img]

Trijicon TA51:
[img]http://www.trijicon.com/parts/TA51.jpg[/img]

The TA51
[img]http://www.trijicon.com/parts/TA51.jpg[/img]
is used on "Colt Military Style Rails". It should work on your BFI flat top.

The TA51W
[img]http://www.trijicon.com/parts/TA51.jpg[/img]
is used on Weaver rails.

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