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Posted: 3/13/2012 1:11:37 PM EDT
| I have a 4x32 ACOG on my 14.5 inch SBR. I was at the range today shooting XM193 @100 yards. I was not happy with the groupings I was getting. 4 to 6 in grouping. So I put my wi Aimpoint Comp M3 and a 3x mag back on, and the groupings were way better. I cant seem to fiquire out why. My groupings with the Aimpoint and 3x are way better (nearly 3 inches tighter). I cant fiquire out why. I was also using my AAC M4 2000 suppressor during the range trip. I am going to go back out tomorrow (if i get off of work early enough), and try out some XM855 and see if there is a difference. |
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I have seen similar results. I had a TA11F and a TA33-R8. At the bench, I could not see any difference between my groups compared to my Aimpoint M4, M3, or T1. In the field (dropping to one knee for the shot) hunting stationary jackrabbits from 25yds to 150yds, I actually did worse with my ACOGs compared to my Aimpoints.
It seems like it should be the opposite. |
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I have seen similar results. I had a TA11F and a TA33-R8. At the bench, I could not see any difference between my groups compared to my Aimpoint M4, M3, or T1. In the field (dropping to one knee for the shot) hunting stationary jackrabbits from 25yds to 150yds, I actually did worse with my ACOGs compared to my Aimpoints. It seems like it should be the opposite. I totally agree I was shocked to how bad my groupings were with the ACOG. I was in the Prone Mag assisted then in the prone firing off of a bag. My Aimpoint groupings were exremely tight. Hell even firing with my Aimpoint without the 3x had better results. |
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I have a couple theories why I did worse in the field looking back on this (I have since sold my ACOGs).
I think what was happening was that the chevron on my ACOG was blooming in the hot desert sun. I zerod my rifle at a bench with a cover and had a crisp aiming point. As a result of the increased light to the chevron, my POI was all messed up. Because I was shooting at small targets, this POI problem was enough to cause misses. I also think that it can actually be harder to hit small targets with magnification without artificial support in hastily assumed field positions. You notice the wobble more due to being able to see more. I think an ACOG reticle that blooms uniformly would be better (horseshoe, crosshair, ect...). Maybe shooting sticks would be an improvement too. But, for shooting off one knee, I think the ACOG and the Aimpoint will be very close in performance. |
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I had a similar issue when sighting mine in. I ended up loosening the mount, and holding it forward in the rail slot while I cranked the thumb screws with a quarter. I know that applies to bolt action reifles, but because of the bolt slamming forward, arent you supposed to mount optics on AR's toward the back of the rail? |
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Well for the amount of money these scopes cost so far I am not impressed at all. I know I am a good shot, but groupings I got today really worked my nerves. Minute of man my friends - that's what matters. Look at what ACOG stands for again: Advanced COMBAT Optical Gunsight Take your rifle and drop it from the bench, then slid it across the hummer floor and let it sit in the sun for weeks. Then rack the rifle, put the chevron on the enemy who is advancing on you and pull the trigger - bet you still get a hit :) Not going to win any paper MOA matches, but what it does it does well. But yea, maybe it's parallax that gets most people. You move a little between shots and parallax can widen your groups. |
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It is not the mount in my experience. I used Larue and it was tight.
Minute of man is a flawed theory in my opinion for the basis of a scope. When the shooting starts, I expect few "men" to be standing around waiting to be shot. More likely, it will heads, feet, and other body parts. People hide when bullets are flying. |
| In my experinces, Aimpoints are very forgiving about head position while ACOGs are not. Moved all my ACOGs to rifles that I tend to get a repeatable head placement - A2, ACR, M1A. On my M4 clones and para FAL, I went with Aimpoints for the most part. The absolute worse paring I tried was M648 ACOG on my FAL. |
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It is not the mount in my experience. I used Larue and it was tight. Minute of man is a flawed theory in my opinion for the basis of a scope. [violet]When the shooting starts, I expect few "men" to be standing around waiting to be shot[/violet]. More likely, it will heads, feet, and other body parts. People hide when bullets are flying. You would be surprised. Be that as it may I like the new M4S CCO I am issued or a nice ACOG with crosshairs. |
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I have limited experience with ACOG's. However my shooting team's extensive experience coupled with mine are not typical of the OP's issues.
I think parallax is the issue here. I don't know what it is set at, but most non parallax adjustable scope are set at at least 150 yards. Next time pay very close attention to your head position and try to repeat it as much as possible. You might even put a piece of tape on your stock as a reference point. See if that helps. Better yet, try the same grouping at 200 yards and see if it is better. It would stand to reason that the parallax would be set further out than 100 where a scope is going to be of more benefit anyway. |
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What type of target are you using? Is it one that you can get a repeatable hold on with the reticle you are using? Is the ACOG tight in it's mount? Is the Mount tight to the upper receiver? Is your cheek weld consistent? I shoot nose to charging handle and when I am going for absolute precision, try to make sure there is a slight but even black ring in the scope view - that way I can be sure I am being consistent with my cheek weld and eye relief.
Ultimately the optic doesn't change the mechanical accuracy of the gun/ammo - it's just a matter of how consistent you are being with sight alignment and trigger control. It's also worth considering that magnification can make your wobble more apparent, and result in rushed shots and jerked trigger pulls. Make a nice little target - say a 1/2 inch square - and set it up 10 yards away in your house - spend time dry firing with the new optic, getting comfortable breaking the shot with the chosen point of aim aligned in the target area. Sounds stupid, but it is good practice calling your shots and getting comfortable with the reticle. |
| Update I was back at the range today. I used a consistant cheek weld and I made sure all the screws were tighten. The groupings inproved a little at 100 yards (ruffly 3 ito 4 nch grouping), but this grouping is still larger then my groupings with a aimpoint and 3x mag. |
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Update I was back at the range today. I used a consistant cheek weld and I made sure all the screws were tighten. The groupings inproved a little at 100 yards (ruffly 3 ito 4 nch grouping), but this grouping is still larger then my groupings with a aimpoint and 3x mag. There really isn't anything unusual about getting a 3-4" group with XM193. I would suggest using more accurate ammo because unless you've taken a large sample size with each optic it really could be a coincidence getting different group sizes. I don't see parallax being the issue because you introduce parallax into the aimpoint equation once you start using the magnifier. |
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1. Check screws to make sure they are tight
2. Put a piece Of electrical tape over fiber optic tube on top to control light and reduce bloom on applicable models. 3. After an adjustment wack your ACOG to reset the prissim to new adjustment. Or else it will take a round or two to settle in to new adjustment. FYI I went to an instructor course put on by trijicon. This is what the told us to do. It was a train the trainer course because we started teaching ACOGs AR the school of infantry. Hope this helps! |
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At 100m, you aim with the top of the donut, at 200m, with the middle, and at 300m, the bottom of the donut. Not exactly super precision shooting but the upside is that the donut is perhaps the fastest reticle the ACOG has. It's highly instinctive.
I noticed some parallax, so it's essential to maintain the same position. Is your rifle free floated? If not and you put too much pressure on the barrel on the sandbags, it could throw off your groups. I did that once and it drove me crazy as it happened intermittently. I would eliminate all other factors before looking at ACOG. |
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