Swifty Morgan
New member
Right now I am finishing work on my prone shooting platform. Once I get it in place, I'll get back to testing the AR-15.
Problems Moving from 50 to 100 Yards
- Thread starter Swifty Morgan
- Start date
One thing I found out after far too long, do not trust the scope seeings for Parallax.
Focus it in at 100 yards, do not set it. I had issues with one scope that was erratic all the time (setting and seeing the dot) until I read that the markings are only rough guide.
That said you also cannot just say about 1.5 MOA. You have to measure it, frankly its easier if you do it in inches for 50 and 100 yards. Very see the variance.
Focus it in at 100 yards, do not set it. I had issues with one scope that was erratic all the time (setting and seeing the dot) until I read that the markings are only rough guide.
That said you also cannot just say about 1.5 MOA. You have to measure it, frankly its easier if you do it in inches for 50 and 100 yards. Very see the variance.
reynolds357
New member
I used to think AR rifles were not MOA shooters. I just fed them crap and got scatter gun groups. Then I happened to get colt upper that just happened to group the junk ammo I fed it at less than MOA. Then I figured out all my uppers will do it with load development.
I then decided I would go all out and build a fully blue printed upper with a $500+ match barrel. That stupid thing consistently shoots 2" at 400 when I get the wind read right.
Swifty Morgan
New member
My long-range instructors told my class not to pay much attention to parallax-knob markings.
I'm comfortable saying "about 1.5 MOA." It's not like 1.05" and 1.60" look all that similar without a ruler. Or, at 50 yards, 0.5025" and 0.8".
I'm comfortable saying "about 1.5 MOA." It's not like 1.05" and 1.60" look all that similar without a ruler. Or, at 50 yards, 0.5025" and 0.8".
Your cheek weld is something you should be able to get into consistently because changing how your body contacts the rifle will change the point of impact. Sometimes it is significant. I've always had to dial in about a moa of right windage when I got to sitting from standing because, in the sitting position, the gun is a little less squarely on my shoulder than in standing. Hence, recoil slides the gun butt a little more toward my shoulder, causing the muzzle to move a moa to the left before the bullet gets out. My prone needs another moa of adjustment to the right with the 30's but not with the mouse gun.
Parallax is good to adjust for a couple of reasons. Having a consistent cheek weld can keep your groups as tight as they are going to be at any range, regardless of parallax. But your come-ups or windage settings may not quite match ballistic tables or other people's come-ups or windage if your parallax is right at one range and wrong at others. If your hold just happens to align your eye perfectly with the scope tube axis, then it won't be an issue. But if your eye isn't perfectly centered, an offset error occurs that grows as the range gets further from the one for which your parallax is correct. Also, as mentioned in the video, the target and reticule are clearer with correct parallax because your eye isn't having to pick one or the other as the point of best focus. Both will be within the range of your eye's ability to adjust focus, but having the virtual image of the target on a different plane from the reticule can fatigue your eye noticeably during a long match or range session by forcing it to correct the focus rather than staying relaxed.
Regarding the change in moa for bullets with range, Bart's explanation is one part. The other is that groups tend to disperse by drift introduced by slightly off-axis bullet mass or physical imperfections in the base or muzzle crown or by the bullet exiting the muzzle while the muzzle has some lateral movement, etc. The drift can be measured in inches per second away from the ideal trajectory path. As the bullet goes downrange, it is slowing down so that each successive 100 yards has a longer time of flight than the previous 100 yards did. That longer TOF gives the drift more time to move the bullet more moa away from the axis, so the group moa on the paper increases. In general, the drift is too slow to have significant drag opposing it, so it doesn't slow down appreciably and is certainly nowhere near to proportional to the drag slowing the bullet's forward travel.
Parallax is good to adjust for a couple of reasons. Having a consistent cheek weld can keep your groups as tight as they are going to be at any range, regardless of parallax. But your come-ups or windage settings may not quite match ballistic tables or other people's come-ups or windage if your parallax is right at one range and wrong at others. If your hold just happens to align your eye perfectly with the scope tube axis, then it won't be an issue. But if your eye isn't perfectly centered, an offset error occurs that grows as the range gets further from the one for which your parallax is correct. Also, as mentioned in the video, the target and reticule are clearer with correct parallax because your eye isn't having to pick one or the other as the point of best focus. Both will be within the range of your eye's ability to adjust focus, but having the virtual image of the target on a different plane from the reticule can fatigue your eye noticeably during a long match or range session by forcing it to correct the focus rather than staying relaxed.
Regarding the change in moa for bullets with range, Bart's explanation is one part. The other is that groups tend to disperse by drift introduced by slightly off-axis bullet mass or physical imperfections in the base or muzzle crown or by the bullet exiting the muzzle while the muzzle has some lateral movement, etc. The drift can be measured in inches per second away from the ideal trajectory path. As the bullet goes downrange, it is slowing down so that each successive 100 yards has a longer time of flight than the previous 100 yards did. That longer TOF gives the drift more time to move the bullet more moa away from the axis, so the group moa on the paper increases. In general, the drift is too slow to have significant drag opposing it, so it doesn't slow down appreciably and is certainly nowhere near to proportional to the drag slowing the bullet's forward travel.
You are quite correct, but since the op did not mentioned type of AR my statement holds true as well and you can definitely have AR's that shoot sub moa. For example my Rock River Arms I purchased came with a 3/4 moa guarantee at 100 yards, mine does better with factory ammo from Hornady superformance 75 grains BTHP, and gets even tighter with reloads.
Swifty Morgan
New member
I don't know what this gun will do. I just know it was not far from 1 MOA at 50 yards, and my hope is that with better training and equipment, I will shoot better.
Scope or user error , one step at a time . A good steady shooting position , trigger control , cheek weld eye relief . Check scope mount , scope set up , rings aren't to loose or too tight , canted reticle and parallax issues . If all is good then I would go try a different scope if you have one before going with another barrel.
reynolds357
New member
If your scope eye is 20-20, the parallex markings will be dang near dead on in quality scopes.
Swifty Morgan
New member
Today I set up my new shooting platform, and I got the AR-15 out. I will post the target. I had various issues, so I only shot 30 rounds before quitting.
I did what I could to fix the parallax.
The bottom left bullseye is a mess, but fortunately, it turned out the scope mount was loose. I had installed it according to the instructions, but I must have made a mistake.
The target to the bottom right was next. I had adjusted the scope, so the grouping, if you can call it that, moved.
The top left bullseye was last. It seems to me that things started to come together. I had a couple of flyers, but other than that, the impression I have is that this gun would shoot sub-MOA but for a technique problem. The vertical dispersion is very tight, but I got horizontal stringing.
If it will tighten up vertically, doesn't that suggest that it should be able to shoot well horizontally if I get it together?
I thought I loved the trigger, but right now I don't. It's a LaRue MBT-2S. It's crisp and all that, but the pull is heavy for what I'm trying to do. I was taught to put the trigger pretty far out on my finger, and that makes it harder to pull, so maybe this trigger isn't for me.
The bipod seems to insist on leaning farther and farther over as I shoot, so it has to be straightened over and over. Maybe it's just a matter of tightening it. I don't know if it could cause stringing.
I can't complain about doing this well with factory ammo and an $800 gun, but it sure looks like the gun can do better.
Anyway, suggestions welcome.
I did what I could to fix the parallax.
The bottom left bullseye is a mess, but fortunately, it turned out the scope mount was loose. I had installed it according to the instructions, but I must have made a mistake.
The target to the bottom right was next. I had adjusted the scope, so the grouping, if you can call it that, moved.
The top left bullseye was last. It seems to me that things started to come together. I had a couple of flyers, but other than that, the impression I have is that this gun would shoot sub-MOA but for a technique problem. The vertical dispersion is very tight, but I got horizontal stringing.
If it will tighten up vertically, doesn't that suggest that it should be able to shoot well horizontally if I get it together?
I thought I loved the trigger, but right now I don't. It's a LaRue MBT-2S. It's crisp and all that, but the pull is heavy for what I'm trying to do. I was taught to put the trigger pretty far out on my finger, and that makes it harder to pull, so maybe this trigger isn't for me.
The bipod seems to insist on leaning farther and farther over as I shoot, so it has to be straightened over and over. Maybe it's just a matter of tightening it. I don't know if it could cause stringing.
I can't complain about doing this well with factory ammo and an $800 gun, but it sure looks like the gun can do better.
Anyway, suggestions welcome.
