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10/20/2017 1:01:18 AM
9/22/2017 12:11:25 AM
Posted: 8/31/2005 1:11:34 PM EDT
I hit the range yesterday, determined to get my AR10 with TA11C sighted in with my new go-to ammo, the 155 grain TAP. I'm using a 50 yard center of donut zero, which actually matches the BDC trajectory as well as anything else with this load. Firing from sandbags off of a bench and after adjustments, I got about a 2 inch group, roughly surrounding the center.

How well should I be able to shoot with the donut at 50 yards? I shoot just as well with my unmagnified EOTech, so it seems I should be doing better with the ACOG. What types of groups do you guys like to get for sight-in?

Before, I had just been using Aussie surplus, so I could shoot a lot of rounds and slowly get closer and closer to POA=POI, over a lot of sessions, but at $1 per shot with difficult availability, I don't really want to expend any more ammo than necessary with the TAP.
Link Posted: 8/31/2005 1:49:48 PM EDT
[Last Edit: 8/31/2005 1:53:31 PM EDT by Face_N_The_Crowd]
I have never shot your tube, nor the ammo in question....... however based on the firearms I own (including 2 AR10's) and the ammo I have shot - surp to hand loads....

At 50 you should have one ragged hole

Edited to add:

The doh_nut is a 4 MOA circle. It is intended to be zeroed such that the top of the outter circle corresponds with POA/ POI - using the middle is going to be less than optimal.

Good luck
Link Posted: 8/31/2005 2:32:59 PM EDT
I have shot 0.5 MOA groups using the top of the donut @ 100 yards.

Link Posted: 8/31/2005 4:20:53 PM EDT

Originally Posted By Zak-Smith:
I have shot 0.5 MOA groups using the top of the donut @ 100 yards.




That was my original plan as well-- to use the top of the donut. I can't get any kind of consistant grouping with that sight picture though. Any thoughts on how to do it?
Link Posted: 8/31/2005 4:23:54 PM EDT
First, cover up the fiber optic with some tape or around with some rubber tubing. You need to pretty much cover it up entirely. A dull red is OK, but you don't want it bright.

Second, shoot at something approx 1 - 1.5" in diameter with good contrast on the background. I use those orange "Target Dots" stuck on the white side of an IPSC target.

-z
Link Posted: 8/31/2005 5:55:03 PM EDT
[Last Edit: 8/31/2005 5:55:24 PM EDT by Kreutzberg]
Thanks for the tips--I'll definitly give them a go next time out-- my problem when I tried to use the top of the donut was side-to-side movement. What type of rest do you use to minimize shooter error? Front sandbags only, or something in the rear as well?
Link Posted: 8/31/2005 7:39:02 PM EDT
For accuracy, bag everything. Concentrate on that good sight picture and press.

I just do that to verify the optic is properly zeroed. My ACOGs stay zeroed real well, and I pretty much never have to rezero them unless switching guns.

Realistically, the ACOG is not an optic to shoot groups with. Make sure you get a reasonably small group centered around your POA, and then go to town on "practical" targets from 0 - 500 yards.

-z
Link Posted: 8/31/2005 7:44:27 PM EDT
Yep, thats the plan. I like to know that if I do miss, it's due to my poor shooting, rather than the sights being off. Thanks for all of your help.
Link Posted: 9/7/2005 6:54:37 PM EDT
TAG
Link Posted: 9/7/2005 8:22:23 PM EDT
Link Posted: 9/7/2005 11:40:00 PM EDT
Another trick I have used with "donut" ACOGs is to put up a black bull that is just slightly larger than 4 MOA (i.e. ~ 5 inch bull or a custom size made on your PC) .

Then center the donut on the bull and shoot ... bullets should hit top part of black at 100, not too hard to keep faint black rim.
Link Posted: 9/8/2005 5:05:28 AM EDT
[Last Edit: 9/8/2005 5:07:17 AM EDT by bjwar10]
I've got the chevron (TA11E) and have never used the donut but knowing where I have to aim at 25-75 yards when the tip of the chevron is zeroed at 100...wouldn't the center or slightly above center of the donut be perfect for short range given the top of the donut is zeroed at 100? Just a thought.

ETA: What kind of mount do you have tour TA11 in? I seem to remember a pic and thought you were using a LT...if not it could be the mount. My TA55 mount would hold zero very well.
Link Posted: 9/8/2005 1:34:25 PM EDT
Since I just got my TA31 I haven't had a chance to get to the range yet, but I thought the point of having the donut was to put the bullet where the hole is?
Well in the manual it states "The reticle is designed to be zeroed at 100 meters with the top of the reticle being the point of aim. yada yada yada... The reticle may also be zeroed at 25 meters if the 300 meter mark is used or the bottom of the illuminated reticle. A 25 meter zero is less precise than a 100 meter zero"

Would it actually be possible to adjust the elevation to a point where the center of the donut is the zero at 100 meters?
Link Posted: 9/8/2005 1:38:43 PM EDT
You can zero any part of the reticle for whatever distance you want, but then the BDC will be wrong, obviously.

A 50-yard center of donut zero is basically equal to a 100 yard top of donut zero.

The BDC from Tijicon is designed to work with the specified load with a 100 meter zero on the top of the donut.


Link Posted: 9/8/2005 1:48:59 PM EDT
Cool thanks,
I will mostly be shooting 50 -100 yards, so if 50 is around center than I should be fine with the 100 being around the top of the donut. The manual doesn't state anything about this being calibrated for a specific grain round. Also the manual DOES state that the TA31 is calibrated for the top of the CH. Now I removed my CH and mounted on a LT mount. Hopefully I won't have issues.

Thanks again.
Link Posted: 9/8/2005 1:50:49 PM EDT
The impact of sight over bore distance changes on trajectory is slim, as long as they're not gross.

I believe the base TA11/TA31 models are calibrated for M193 from a 20", on the CH.
Link Posted: 9/8/2005 1:55:50 PM EDT
Right now I will be putting BHBB 55g FMJ through my 14.5" M4.

I will be getting XM193 as soon as the ammoman gets more in.
Link Posted: 9/8/2005 2:26:50 PM EDT

Originally Posted By Zak-Smith:
You can zero any part of the reticle for whatever distance you want, but then the BDC will be wrong, obviously.

A 50-yard center of donut zero is basically equal to a 100 yard top of donut zero.

The BDC from Tijicon is designed to work with the specified load with a 100 meter zero on the top of the donut.




That's what the manual that came with my TA-11 said. Zero the top of the chevron at 100 yards and the BDC works out. And I might add, it works GREAT!

Still I keep my Aimpoint for the "fast" work under 200 yds.
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