Zeroing ACOG TA31F

[sabrewulf]

Hi, I haven't had a chance to zero my new ACOG TA31F (4x32 red chevron with BDC). The manual it came with says the right name and model on the front, but at the zeroing portion it has the donut reticle instead of the red chevron. I managed to find another manual for a 3x model. Is it safe to assume that all chevron reticles are zeroed the same way as shown here:

[C4IGrant]

Hi, I haven't had a chance to zero my new ACOG TA31F (4x32 red chevron with BDC). The manual it came with says the right name and model on the front, but at the zeroing portion it has the donut reticle instead of the red chevron. I managed to find another manual for a 3x model. Is it safe to assume that all chevron reticles are zeroed the same way as shown here:

I typically just zero the tip of the triangle or chevron at 50yds (as you most likely NOT going to using the barrel length and ammo they set the zero up for).



C4

[SHIVAN]

The TA31F should be zeroed at 100m, in order to have the stadia lines correspond the the numbers listed next to them. You can zero at any distance you like, but the stadia lines will intersect with the bullet flight different than the numbers indicate, and you'll need to verify these intersections.

You can also zero at zero at 25m by placing the tip of the vertical line like this for aiming:


But as you can see, you should be shooting at 100m and using the tip of the chevron for the most precise method.

Also just as added info:

[FPembleton]

These are excellent diagrams. However, what would be the best aiming points for 15m, 50m, and 75 meters when taking into consideration the offset of the optic?

Thanks

[Dirty McCurdy]

I just use the tip of the cheveron up to 100meters, I think you POI only shifts like 2 inches which to me seems accurate enough for a combat sight.

[Shotdown]

I have the TA31F owners manual in .PDF. If you want a copy, send me your email address.

It's a lot easier to sight it in at 25m with the 300m post. Then verify at 100m with the tip of the chevron.

[JSantoro]

With the TA31F, you're ballistically closer to a 100m zero if you do it at 33m (36 yards). 25m will still work, but expect to print fairly low @ 100m.

Phase I: POA/POI @ 33m or 36yd, using the 300m aimpoint, per the diagram above. 9clicks/inch.

This is a field-expedient method, designed to ensure you are on paper @ 100m. You still need to do a 100m *METERS, NOT YARDS!* zero to be balls-on @ 100m. Going from 33m to 100m, the trend is for your group to be 1/2"to 2" low. If you insist on measuring in yards, make it 109 yards (which = 100m). The 27' of difference between a 100yd (incorrect for the BDC) and 100m (correct for the BDC) zero will make or break you with shots beyond 300m.

Phase II: POA/POI @ 100m, using the tip of the chevron to confirm/fine tune. 3 clicks/inch.

In between ANY and ALL adjustments, don't forget to replace the caps on the adjusters and give the windage adjuster a solid thump with the heel of your hand. This ensures that the prism is set in both axes of movement. If you don't, your next shot will certainly follow whatever adjustment you did, but the next ones may not because the prism may move under the recoil impulse.

Phase III: PROFIT!!

EDIT: Your optic height-over-bore is 3.755" with your LOS crossover being 33m. You can chart stuff like that on a ballistic calculator, or use the 300m aimpoint as a good place to start, but you will have to figure out the specifics for yourself. Generally, though, the idea is "red you're dead," i.e., from 0-300m, get the chevron on the center of the visible mass of your target, apply what fundamentals you can given your situation and press rounds until you get to Phase III or can judge your impacts and adjust enough to get you to Phase III.

Of course, if you have a green or amber reticle, the idea is the same but the ditty loses cuteness because it doesn't rhyme.

[sabrewulf]

With the TA31F, you're ballistically closer to a 100m zero if you do it at 33m (36 yards). 25m will still work, but expect to print fairly low @ 100m.

Phase I: POA/POI @ 33m or 36yd, using the 300m aimpoint, per the diagram above. 9clicks/inch.

This is a field-expedient method, designed to ensure you are on paper @ 100m. You still need to do a 100m *METERS, NOT YARDS!* zero to be balls-on @ 100m. Going from 33m to 100m, the trend is for your group to be 1/2"to 2" low. If you insist on measuring in yards, make it 109 yards (which = 100m). The 27' of difference between a 100yd (incorrect for the BDC) and 100m (correct for the BDC) zero will make or break you with shots beyond 300m.

Phase II: POA/POI @ 100m, using the tip of the chevron to confirm/fine tune. 3 clicks/inch.

In between ANY and ALL adjustments, don't forget to replace the caps on the adjusters and give the windage adjuster a solid thump with the heel of your hand. This ensures that the prism is set in both axes of movement. If you don't, your next shot will certainly follow whatever adjustment you did, but the next ones may not because the prism may move under the recoil impulse.

Phase III: PROFIT!!

EDIT: Your optic height-over-bore is 3.755" with your LOS crossover being 33m. You can chart stuff like that on a ballistic calculator, or use the 300m aimpoint as a good place to start, but you will have to figure out the specifics for yourself. Generally, though, the idea is "red you're dead," i.e., from 0-300m, get the chevron on the center of the visible mass of your target, apply what fundamentals you can given your situation and press rounds until you get to Phase III or can judge your impacts and adjust enough to get you to Phase III.

Of course, if you have a green or amber reticle, the idea is the same but the ditty loses cuteness because it doesn't rhyme.

Good advice, thanks. I've also read about shooting a single shot off target to let the prism settle in after adjustments.

[JSantoro]

No.

Not only no, but hell no, because then you don't know where it's settled until the shot after that oneyou used to settle (or in that case, misadjust) the prism. Whereupon you're more likely to have to do yet another adjustment that you would otherwise not have needed to do.

EVERY round you fire deserves a sight picture, not just buried in a berm. Wasted.

Adjust, thump windage, shoot to confirm adjustment. Lather, rinse, repeat until POA/POI at specified range.

[hrt4me]

Which bullet weight and muzzle velocity correspond the best to the TA31F reticle?