I've just begun trying to use my AR15 (M4A3) at the 100 yard range; I previously took it a few times just for 25 yards. Maybe I'm dense or something, but there's some things that are puzzling me. I'd appreciate any feedback about what may be going on and what I am doing wrong. I want to sight in my rifle and then be able to effectively use it at varying distances (although not 300+ yards since I currently only have access to 100 yards).
First, I sight in at 25 yards. I have seen many different descriptions of how to sight in. Some say do it with the 6/3 mark selected on the rear elevation dial, while others say turn it one click lower, or one or two clicks higher. I'm not sure I fully appreciate the reasoning behind any of those, since I never read an explanation as to why a particular technique for sighting in should be used.
Anyway, this weekend I went with the explanation in the Bushmaster manual. It said to put it on 6/3 first then move the knob up two clicks (i.e. the direction that'll eventually get you to 4, 5, 6). I'm not entirely sure why, since I'd expect closer distances to need it lower. Anyway, using the iron sights and a front rest, and adjusting the front post, I got 1" groups at the point of aim 25 yards away. Cool. Then I went home.
Today I tried again at 25 yards, still good... 1" group at 25 yards without having to adjust anything.
Then I put the target at 50 yards. Now, the group is still 1" but it is 2" over where I was aiming. (Keep in mind I still left the elevation knob at the position I used to sight it in... I didn't move it back to 6/3 because I was curious what would happen if I left it alone). I wasn't too happy about the impact locations, but it did give me some data.
Then, I put target at 100 yards. With my spotting scope, I couldn't even tell where the holes were. When I went over, there was a 1" group but it was 6" over where I was aiming, and off the top of the paper.
So, the question is why? What exactly is going on with the path of the bullet in relation to how the sights are lined up to make the bullets go an entire 6" too high in a mere 100 yards? I doubt I was aiming too high but I suppose its possible.
What would be the math I would use to determine where I should expect the bullets to go at 100 yards if I moved the knob 2 clicks back to 6/3?
Since I zero for 25 yards but the minimum position of the knob is for 300 yards (unless you count that one more click lower it'll go whatever that is for), what do people generally do if they want to be accurate at 100 yards (not 300 yards)?
First, I sight in at 25 yards. I have seen many different descriptions of how to sight in. Some say do it with the 6/3 mark selected on the rear elevation dial, while others say turn it one click lower, or one or two clicks higher. I'm not sure I fully appreciate the reasoning behind any of those, since I never read an explanation as to why a particular technique for sighting in should be used.
Anyway, this weekend I went with the explanation in the Bushmaster manual. It said to put it on 6/3 first then move the knob up two clicks (i.e. the direction that'll eventually get you to 4, 5, 6). I'm not entirely sure why, since I'd expect closer distances to need it lower. Anyway, using the iron sights and a front rest, and adjusting the front post, I got 1" groups at the point of aim 25 yards away. Cool. Then I went home.
Today I tried again at 25 yards, still good... 1" group at 25 yards without having to adjust anything.
Then I put the target at 50 yards. Now, the group is still 1" but it is 2" over where I was aiming. (Keep in mind I still left the elevation knob at the position I used to sight it in... I didn't move it back to 6/3 because I was curious what would happen if I left it alone). I wasn't too happy about the impact locations, but it did give me some data.
Then, I put target at 100 yards. With my spotting scope, I couldn't even tell where the holes were. When I went over, there was a 1" group but it was 6" over where I was aiming, and off the top of the paper.
So, the question is why? What exactly is going on with the path of the bullet in relation to how the sights are lined up to make the bullets go an entire 6" too high in a mere 100 yards? I doubt I was aiming too high but I suppose its possible.
What would be the math I would use to determine where I should expect the bullets to go at 100 yards if I moved the knob 2 clicks back to 6/3?
Since I zero for 25 yards but the minimum position of the knob is for 300 yards (unless you count that one more click lower it'll go whatever that is for), what do people generally do if they want to be accurate at 100 yards (not 300 yards)?
