AR15 Trajection Issues!

Bullet Hole Bailey · 12-23-2010, 05:07 PM

Well, after a recent build and "Breaking in" the barrel, I took the AR out to sight it in. I was resting on a sandbag and at 25 yards, I got it to where it was dead on. From there I went straight to 100 yards. I took a 3 shot group, then inspected. On a paper plate, there was not a single shot on it. I was extremely perplexed!!

After many more shots I discovered that it was shooting about a foot high! and I have no idea why!

Does anyone know why, or how my AR could be on at 25 and way high at 100?

Thanks

herb40 · 12-23-2010, 05:39 PM

When you go back out zero it at 50 yds. You should be about 2" high at 100 yds, pretty close to 200 zero.

Centaur 1 · 12-23-2010, 05:42 PM

Your line of sight on an AR is much higher than the line of the bore. In order for the bullet to cross your line of sight at only 25 yards it will be very high at 100 yards. Even on my 30-06 with a 32mm scope and low mounting rings, a 25 yard zero is 3" high at 100 yards.

Bullet Hole Bailey · 12-23-2010, 05:57 PM

That would make sense, becasue I do have extra tall rings on it, thank you!

Ridge Runner · 12-24-2010, 05:57 AM

the center of a scope is about 3" from center of bore on a typical AR, so if you set the scope to angle the bullet up 3" at 25 to intersect the line of sight, then your raising the bullet 6 inches at 50, 9inches at 75 and yep 1 foot at 100 yards.However you sight in 1 inch high at 100, then your raising the bullet 4 inches at 100, 3 at 75, 2 at 50 and 1 inch at 25, so it should be 2 inches low at 25 to start.RR