Bang4theBuck
Well-Known Member
My guess is spin drift, and possibly some wind that you can't see or feel from your shooting position. I've also had this issue when the parallax wasn't aligned with my yardage.
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MOA or bust
Well-Known Member
You must have a solid 100 yard zero. One or two shots close to bullseye is not good enough.
If you have windage change at distance it can mean that your scope and bore are not perfectly aligned. Not all actions are perfect and not all scope rails are perfect. A set of Burris rings with inserts can fix your problem.
Or just toss that supressor in the ditch, go back to a brake and be happy 
. Only partly kidding. I think all the others are spot on. I have the worst results with supressors. My rifles shoot completely different with them but I will say that if your zero is slightly right it will correlate way down range. May just look like it's trending on the right side of the POI dot at 100 but even a 1/4 minute that's hardly noticeable at your 100 yard zero gets exponentially larger. It's happened to me. If everything else is checking out I'd shift my zero slight and see how it affects groups stepping out.
. Only partly kidding. I think all the others are spot on. I have the worst results with supressors. My rifles shoot completely different with them but I will say that if your zero is slightly right it will correlate way down range. May just look like it's trending on the right side of the POI dot at 100 but even a 1/4 minute that's hardly noticeable at your 100 yard zero gets exponentially larger. It's happened to me. If everything else is checking out I'd shift my zero slight and see how it affects groups stepping out.
Tommy T
Well-Known Member
At a 1K yds you will have 6 to 7" spin drifts and if your scope is not plumb with you rifle that will also throw it off if your scope is 5 degrees off at a 1K yds your looking at around 24to 30"
dallen0427
Well-Known Member
Do a tall target test to see if your perfectly plumb. It will also give you info on offset to plug into your ballistic app.
Very seldom does a rifle have the same exact zero at different ranges. Elevation changes, usually the bullet drops unless the zero you are using for the different ranges is off, which is often the case. Just because your ballistics chart says that the drop will be this, and you dial it in only to find that it isn't working is not unusual. I would suspect that the elevation zero you are using is off causing the hit to be high. Simply reset the zero you are using at that range to correspond with the hit and that will take care of that problem. The drift to the right, is just that. Spin drift is often overlooked but at longer ranges there are other factors that come into effect, also often overlooked. Wind is a big factor. It may be dead calm on the firing line, but between you and the target the wind can vary, and even reverse itself as the bullet progresses to the target. There were many times when shooting competition when the wind flags along the range showed different direction and speed. I remember once when shooting 600 yards that the wind was off my back on the firing line, halfway down range it was showing 10 mph from the right and at the target it was showing 5 mph from the left. This often happens when you are shooting at a range that is located in a valley or other constricted terrain.
Other things that you might not have encountered or paid attention to is light and mirage. In bright light you can see the target better so your point of aim, be it 6 O'clock or center, you can see better so your hold is going to be tighter thus more accurate. When the light gets darker then you can no longer see the target as clearly so you cannot hold as accurately, your shots will not group as tight as they do in bright light.
Mirage is an optical illusion caused by the heating of the ground under the path of the bullet, causing the air to rise and cause visible (usually under magnification) waves of air currents to rise from the ground into the sky. (Heat rises) and causes the optical illusion that makes the target seem, where it is not. Instead of me trying to explain this phenomenon, I am going to refer you to a video. (a picture is worth 10,000 words)
This is one of the excellent videos available from Midway USA. They have a whole series of videos that explain shooting issues in a manner that is easy to understand. They are very worth your time to review.
Remember, every time you are at the range, you are in competition with yourself. Make each and every shot count and strive to make every shot better than the last.
