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I have a TA01 with the 308 reticle. Was planning on building my first Grendel or 308 with it....oops. That ammo ship has sailed for the time being. I'm now going to put it on a 16 or 20 inch 223 upper. You're saying I should go with the carry handle mount over the quick release mount I have? This model allows me to use iron sights if attached to carry handle.
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No, the .308 models ballistically calibrated for the carry handle are more accurate when mounted via TA51 adapter (or LaRue, ARMS etc) on flat top of a 16" shooting 5.56 75/77gr ammo than any other models.
I find the TA11C to be a near perfect match for 77gr 5.56 ammo (Mk262) from my suppressed (OPS 12th) 16" Recon out past 600 meters.
Your TA01 should have the exact same ballistic reticle.
From the B Roberts ACOG BDC Chart:
.308 Carry-Handle BDC
This BDC is based on a carry handle ACOG firing M852 Match out of a 20" barrel.
ACOGs using this BDC include the TA11C and TA01B.
Stats used to figure BDC baseline: M852 traveling at 2,500fps with a BC of .447 and a height over bore of 3.5"
For a Flattop 20" barrel firing M852:
Sight in at 150 or 0.7" high at 100. You will not deviate more than 0.5" from the BDC all the way out to 600
For a Flattop 20" firing 75gr OTM @2750fps
Sight in at 100 per manual. You'll be dead on to 200, 1" high at 300, 3" high at 400, 6.7" at 500, and a bit over 10" high at 600.
For a Carry Handle 20" firing 75gr OTM
Sight in at 100 per manual. This doesn't match the .308 BDC too well; but it is the best you'll get. 1" high at 200, 3" high at 300, 5" high at 400, 10" at 500 and 15" high at 600.
For a Flattop 16" firing 75gr OTM @2615fps
Sight in at 100 per manual. This is a real close match. Max deviation is 2" at 600m and you'll be within 1" at all other ranges.
For a Carry Handle 16" firing 75gr OTM
Sight in at 100 per manual (for a slight edge, sight in at 125 but if you are good enough to notice the edge, then you probably want a more precise match anyway. You'll be about half MOA out to 600.
There is no data for other .308 rounds or 68gr OTM because I don't have the necessary info to figure it out. If somebody gets me the 68gr info I'll add it; but those wishing SMK data or additional .308 data will need to run the numbers themselves (although I can offer help if you need it).
There is no data for 55gr or 62gr because the .308 BDC is by and large a bad match for these rounds.
As you can see the .308 BDC is an excellent match for the 5.56mm 75gr OTM in most applications.
The TA11E uses a flattop adapter. If the BDC is designed for flattop mounting (2.5" height over bore), this ACOG will be more difficult to match to 75gr OTM use. Use the sight-in procedures given for the regular .308 BDC but figure an extra 1" high at 200, 2" high at 300, 3" high at 400 and so on.