Scope height for short distances

[team sidewinder]

Thinking I knew everything about guns and scopes and a little embarassed that I have to ask this question here of those who know more than me. Not being interested target paper work I usually only shoot gophers with my MP 15-22 at ranges of 10 yards to 35 yards distance. I have a NcStar 4X32 tactical scope and when sighted in at 30 yards dead on my combo shoots 2 inches low at 10 yards and if sighted in at 10 yards dead on it shoots 2 inches high at 30 yards. Anybody got any ideas why this is happening or is this just normal with a scope mounted this much higher than the barrel axis line at these short distances on a AR type rifle ? Had a 3/4 inch riser which I though was the problem so removed it and now have the scope mounted directly on the rail and while the problem isn't quite as bad it still seems to be there. I have other conventional rifles ( non AR style ) scope mounted .22LR rifles that don't seem to exhibit this problem at those ranges and may vary only 1/2 inch at both distances at most. A gopher may only offer a target of 4 inches at best so 2 inches high or low even at these close distances can be a miss. Thought it might be the scope and yes the mounts are tight plus it always holds verticle fine. Those who shoot at longer distances than may not notice this and know I can compensate but it doesn't seem right. Thoughts ? Be gentle.

 

[CrazyFingers]

That's normal for a sight line this high above the bore.

Here's a bit more info on AR-15/M16 Improved battlesight:
http://grburnett.us/guns/ImprovedBattlesightZero.pdf

Bullet drop and point of impact vs. point of aim gets interesting when you have your line of sight 2.6" above the bore. It also seems to confuse people who think the projectile magically rises relative to the bore line before dropping. It doesn't. Keep in mind that you actually hold the rifle with a slight upward tilt to get the projectile's point of impact to match your point of aim. In a 5.56 AR-15, this can cause the bullet's path to cross the point of aim twice, for example, once at 50m and again at 200m. Your POI will be low relative to your POA at 25m and high at 100m.

 

[team sidewinder]

That's normal for a sight line this high above the bore.

Here's a bit more info on AR-15/M16 Improved battlesight:
http://grburnett.us/guns/ImprovedBattlesightZero.pdf

Bullet drop and point of impact vs. point of aim gets interesting when you have your line of sight 2.6" above the bore. It also seems to confuse people who think the projectile magically rises relative to the bore line before dropping. It doesn't. Keep in mind that you actually hold the rifle with a slight upward tilt to get the projectile's point of impact to match your point of aim. In a 5.56 AR-15, this can cause the bullet's path to cross the point of aim twice, for example, once at 50m and again at 200m. Your POI will be low relative to your POA at 25m and high at 100m.

Thank You. I appreciate your input on this.

 

[CrazyFingers]

Here is an extremely simplified diagram of what I'm talking about:

 

[berzerker]

Great diagram!
i've drawn this many-a-times, but some people just won't understand.
even some quite expierenced shooters.

I use my smithy mostly in the 1-25 meter range, often in the 1-50 meter range, with once in a while an excursion to the 100m range.

I have the best results with my scope (1-4x) zero at 25 meters. POI at 50 meters is at the bottom of the 4moa dot and at 15 meters POI is still within the 4 moa dot of the scope.
Closer than 15 meter I have to aim a litttle higher.
at poit blank range (2 m) I have to aim about 12 cm (5inches) higher. about the same as when i shoot at 100meters.

I can live with that

 

[team sidewinder]

Here is an extremely simplified diagram of what I'm talking about:

Thanks. My dilemma seems to be the area where in your drawing targets fall in between the end of the muzzle and where the bullet crosses the trajectory line the first time. I know this pretty close range but like I mentioned in the earlier post it is in the 10 to 20 yard range. This condition just seems more exaggerated on this 15-22 rifle/scope combo even with the scope mounted as low as you can mount it. Even with the scope mounted low and right on the rail it is no problem for me with cheek weld on the stock and now I know I can adjust to it accordingly. Thanks again