Ok guys,

I e-mailed Trijicon, and have yet to get a reply. So I have come to you all.

From their site:
Details: ACOG 4x32 Scope with Yellow Center Illumination for M4A1 - includes
Flat Top Adapter, Backup Iron Sights and Dust Cover.

The TA01NSN was designed specifically for the US Special Operations
Command SOPMOD M4 Carbine.  To meet their requirements, the reticle
bullet drop compensator and range finding stadia lines are based on
the trajectory of the 62 grain bullet from a 16 inch barrel,
flattop mount (Picatinny rail Mil.Std.1913).

Magnification:    4X
Eye Relief:       1.5 in
Exit Pupil:       8 mm
Field of View:    7.0 degrees
Length:           5.8 in
Weight:           9.9 oz
Field of View:    36.8 ft at 100 yds
Adjustment:       3 clicks per inch at 100 yds.

Tritium Activity: 100 milliCuries in one source

My question is this...

A M4A1 has a 14.5 inch barrel, not a 16 inch barrel as we all know. I have a 14.5 barrel and want to get one of these. Will this be tuned for my upper, or am I just being too picky, and shouldn't worry about it.

Read through the [url=www.ar15.com/forums/topic.html?b=3&f=18&t=152794]ACOG BDC thread[/url] tacked to the top of this forum then all shall become clear [:)]

I am sure it was made for M855 from a 14.5" barrel. However, you will never know the difference.  With M193 and a 16" barrel I'm about 2" off at 500 meters accourding to a ballisic calculator.  The 500 meter cross hair covers over 5 inches of the target at that range so my shot is still in the cross hair.  In reality I can't even estimate range that close, and shure as heck not under any stress.

Matt_B
I Don't think the TA01NSN is a BAC scope.

inkaybee
Thanx

Edit: I could be very wrong right now, I am very drunk. My wife and I had a Lg bottle of wine together.

The tacked thread is about BDC-- bullet drop compensation, not BAC bindon aiming concept.

Ok. see above edit!

Edit: Can I just say: I love all of you!!!!!!

Everyone on this forum has been a jewel of info.
No matter how liitle it may seem, or how big!

I mean it!!!!!!!

Thank You To All!!!!!!!

I would believe Trijicon if they e-mailed me and said 16in.

I bought a KAC 600M Buis and the manual said something like:

the BDC markings are a compromise between 14.5 and 20inch barrels and will not "perfectly" compensate for either.

Maybe 18in is what that was designed for but that is because the 600m sight is primarily for rifles and not carbines and since this sight is primarily for carbines and not rifles it would make sense that the sight would be calibrated for a 16inch barrel.