Bushmaster AR 15

[Slot Pursuit]

I need some help. I purchase a use Bushmaster AR 15 with a red dot scope on it and you can zero in at 25 yards and at 50 yard it would be 12 inches off. So though the scope was mess up so I purchase a new scope and rings, samething. Don't know what to do unless the barrel is mess up.

 

[TackleberryMCS]

Something is seriously wrong. You need to have someone check it out.

 

[bigbulls]

It's not physically possible to have a rifle zero at 25 yards and 12" off in any direction at 50 yards. Assuming the scope or red dot is actually holding zero at 25 yards.

 

[TackleberryMCS]

It's not physically possible to have a rifle zero at 25 yards and 12" off in any direction at 50 yards. Assuming the scope or red dot is actually holding zero at 25 yards.

Exactly. I have a feeling there is something really wrong with the optics/mounting setup.

 

[Slot Pursuit]

That is the reason I bought rings and scope.

 

[TackleberryMCS]

Can you provide some pictures of the setup you have along with the specs?

 

[Slot Pursuit]

I can do that.

 

[FrankT]

have you checked the mounting of the barrel and the rail it is mounted on, tight?

 

[HEIST]

I bought 2 cheap red dots. They would hold a zero for a couple of shots then start rising every shot after that. They are to weak for anything stronger than a 22. The recoil effects it to much.

 

[Slot Pursuit]

Tack, I not smart enough to put pictures on here. If you can text me I will send you pic. 850 572 5954

 

[DSPLCD1]

I need some help. I purchase a use Bushmaster AR 15 with a red dot scope on it and you can zero in at 25 yards and at 50 yard it would be 12 inches off. So though the scope was mess up so I purchase a new scope and rings, samething. Don't know what to do unless the barrel is mess up.

I had the same problem awhile back, turned out that I had not been to the eye doctor for a few years. He gave me a new prescription and now I'm dead on!!!!!

 

[Droshki]

For the OP

 

[ksenter]

the scope you have isnt really such a bad scope. I think there is a lot of variable included in the mount on top of a mount. You have a couple areas of opportunity of failure there. One, the riser on top of the rail, if the risers loose, the scope is loose. Secondly, your mounts. If they're loose on the riser, and the riser loose on the picatinny....well, you get the point. Too many variables.

Start with good solid mounts and move forward with that. Alleviate the possible failure points.

One more thing, and I'll stop. The scope/dot approx 1.5-2" over the bore could be leading to your differences from 25-50yds. I cant think of a good way to explain or an illustration to demonstrate, but you are having to aim your scope down pretty good to hit the bullseye at 25yds vs the bullseye at 50yds. Angles

 

[ksenter]

closest I could come up with

maybe someone can comprehend what I'm "attempting" to say and say it better

 

[bigbulls]

the scope you have isnt really such a bad scope. I think there is a lot of variable included in the mount on top of a mount. You have a couple areas of opportunity of failure there. One, the riser on top of the rail, if the risers loose, the scope is loose. Secondly, your mounts. If they're loose on the riser, and the riser loose on the picatinny....well, you get the point. Too many variables.

Start with good solid mounts and move forward with that. Alleviate the possible failure points.

One more thing, and I'll stop. The scope/dot approx 1.5-2" over the bore could be leading to your differences from 25-50yds. I cant think of a good way to explain or an illustration to demonstrate, but you are having to aim your scope down pretty good to hit the bullseye at 25yds vs the bullseye at 50yds. Angles

I definitely agree with the mounting of the scope with better mounts but there is really no reason what you have won't work provided they are attached properly.

As far as the last part, if the scope is 2" above the bore and you are zero at 25 yards you would be approximately 2" high at 50 yards.
I ran the numbers earlier with a bullet with a .5 BC leaving the bore at 3000 fps. You would have to be sighted in to be zero at 950 yards in order to be 12" high at 50 yards.

 

[ksenter]

maybe thats the problem! depth perception!!! :ranger:

 

[ksenter]

btw, I'm not discussing bullet drop, I'm discussing trajectory, or "angle of attack" if you will.

 

[bigbulls]

I know. It all works together.

It is absolutely impossible to get a bullet to be off by a foot in any direction at 50 yards if the rifle is zero at 25 yards. It just can't happen with the rifle pictured.
Something is either broke or the shooter isn't doing their job, or this.

I had the same problem awhile back, turned out that I had not been to the eye doctor for a few years. He gave me a new prescription and now I'm dead on!!!!

 

[Slot Pursuit]

Thanks for the information. I will regroup.

 

[Droshki]

My first thought when I saw the photos was that the riser was not helping things, and ceartinly putting the line of sight way above the bore axis. These two lines can cross at only one (or two if you will) distances. The error at any other distances will be proportional to the difference between the height of the sight line and the bore axis. I believe this is what ksenter was trying to say.

I'd try it without the riser, if you're able.