Looking for advice on sighting in a AR-10 .308

CarolinaColtCollector

CarolinaColtCollector

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I didn’t know if this would be better in the AR platform forum, or the precision/long range page since it *is* a scope setup related question.


I went to sight in my .308 AR-10 this past weekend and was trying for a 100YD zero, we didn’t end up finding anything to attach the target to except for a fence post at about 415ft (orange dot with the arrow). With the heat coming off the field and the target being in the shade, I wasn’t having much luck seeing potential hits so I stopped.


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So while we were sitting there, I adjusted over to this target to the left of my rifle and shot a quick group. Shot placement at that distance was about 8” low and to the right 2”. With that being said, is that something I should try to adjust out with my scope, or should I be looking at something else? Normally at that distance with everything I’ve messed with, it takes a click or two on the scope and it’s dialed in. Or am I potentially shooting at a distance too close? A buddy of mine took his AR-15 and wasn’t having a major difference in POA/POI shift shooting at the same target, at the same distance, with his rifle that has a 100yd zero.
 
Shoot the close target you have there. How far is it? Looks about 40-50 yards? Use a larger piece of paper and aim at a mark in the center. Get your point of impact about 1/2" lower than your point of aim and you will be close at 100. When adjusting your point of impact use the reticle in the scope as a ruler so it will be easier to dial on the corrections.
 
The orange target that is above the rear of my scope is the one that my POA/POI was that far off. It’s about 35 feet from where I was laying on the trailer.
 
Sorry on the computer part of that last part of your post was covered by picture.

I would center the point of impact up and get it about 3 mils low at that distance of about 12-15 yards. What scope is that and what does it adjust in? MOA or Mils?
 
It’s a Vortex Diamondback Tactical 6-24x50. It uses MOA adjustments. I was going to try sighting it in on a nicer day, I just didn’t know if I had enough adjustment to go that far.
 
So it’s ffp and in MOA. Use the reticle like a ruler and After your first shot measure it with a reticle and dial on the correction to get your POI centered and about 17 moa below your POA and it will be close at 100.

You should have enough adjustments to get you to 800+ yards depending on bullet and velocity.
 
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There should be plenty of adjustment in the scope. Is the base 20 moa or 0 moa? Is everything tight? Torque spec on scope rings is 18 inch pounds.


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The mounts and scope are properly attached and torqued, I double checked them before taking it out, I have had that issue before so that was the first thing I checked. Fortunately this one isn’t the quick attach style so it can actually be torqued. Maybe I was just lucky on all the other stuff I’ve messed with? I’ve had red dots and scopes that were always a few clicks off. I guess I was just trying to make sure something wasn’t way off.
 
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So your freshly mounted optic was off with zero adjustments made... and this bothers you because...?

Always get on paper at 25 or 50yds first... easy enough just boresighting. Trying to start at 100yds is wasting ammo.
 
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First off, it is entirely possible that the scope was not zeroed out to the mid-point of adjustment prior to you receiving it, which could result in requiring significant adjustment to align it with point of impact.

I'm not finding anything on the amount of internal adjustment on this optic, so it is also possible that you have enough range of travel to accommodate this correction, but I think to feel better about alignment, I would want to know what it's adjustment range is from the manufacturer.

8" low and 2" right at 50 yards is not unheard of, but it would be best to have bore sighted the optic first. You could remove the upper and ensure it is rested as best as possible and attempt to line up the target in the center of the bore. Then you'll want to adjust the turrets to the center of the target. That has always placed me on paper within a few inches of my intended impact.

So now that you're zeroed in, you need to ask what distance will the rifle most likely be used. Having the information on the adjustment range from the manufacturer should help in determining if you have enough travel to get to where you want to be. If after determining all that you find that your adjustment to be insufficient for your needs, you may want to look at an all-in-one base that incorporates cant (elevation) to your setup. This would give you more range of travel up on your optic.
 
patina said:
So your freshly mounted optic was off with zero adjustments made... and this bothers you because...?
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‘preciate it brother. Because asking a question about something I’ve never experienced is worthy of ridicule.

Grim said:
First off, it is entirely possible that the scope was not zeroed out to the mid-point of adjustment prior to you receiving it, which could result in requiring significant adjustment to align it with point of impact.
Click to expand...

This was the issue. I found out that out of the box, the scope was way off, so I set everything to a general midpoint and it was a LOT closer to get corrected.
 
It's not unheard of to be off so much. I've taken a rifle to have it "professionally" bore sighted and they give it back WAY off.

Make sure to check it all out yourself and you're good to go. The only time I'd be majorly concerned with zeroing a new optic is if impacts are all over the place.
 
It threw me off a little having it come that way straight from Vortex. I’ve mounted 10 or so scopes and a handful of red dots and never would have thought to run the adjustments all over to make sure it was centered.

It made a very consistent ragged hole, just not right. She’s dialed in now though
 
CarolinaColtCollector said:
‘preciate it brother. Because asking a question about something I’ve never experienced is worthy of ridicule.
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Sorry my friend... it just seems you and I have had completely opposite experiences. I have seen very high-end optics come out of the box maxed out one direction or the other. I think this is one way to keep guys who mount them and allegedly bore/laser sight them honest.
 
patina said:
Sorry my friend... it just seems you and I have had completely opposite experiences. I have seen very high-end optics come out of the box maxed out one direction or the other. I think this is one way to keep guys who mount them and allegedly bore/laser sight them honest.
Click to expand...


It’s something I’ll have to check in the future for sure. I’m primarily used to scopes that are 30-40 clicks of adjustment either way for windage, I think this one has ~220 from far left to far right.
 
Doesn't matter if mils or moa. Both work the same way.

OP best to stop thinking and talking in clicks though as it means different things depending on the scope. Speak in either MOA or mils and it will be easier in the long run. No click speak or counting. That's why they put the big numbers on the knobs ;)
 
This is a long conversation.

Shoot close 50yds or less, dial in 1" low. does not matter the distance really as long as the windage is right and the elevation is 1" low its fine.

Go to 100 or even 200 yards, plan on shooting on a 12" target, adjust after that.

DONE
 
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