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Scope on an AR
slinger
Member Posts: 1,401 ✭✭✭
I want to put a 3X9 scope on a Bushmaster E2S on top of the carry handle. Should I be bothered about the barrel centerline being four inches away from the scope centerline? This would be for approx. 300 yard work. Sight it for 300 and change point of aim with the scope reticle for longer and shorter shots? Is this question even understandable?
Comments
A big part of this will be to get a GOOD (not $15 china) mount to the scope on.
Get the lowest rings you can find, and maybe a check piece, and it should work fine.
I want to put a 3X9 scope on a Bushmaster E2S on top of the carry handle. Should I be bothered about the barrel centerline being four inches away from the scope centerline? This would be for approx. 300 yard work. Sight it for 300 and change point of aim with the scope reticle for longer and shorter shots? Is this question even understandable?
Yes, your question makes perfect sense.
You're concerned about the greater-than-usual distance between the scope and the barrel, and how it might affect your zero.
The answer is while several inches between the bore and scope isn't ideal, its certainly workable. In fact, if you are always shooting at one given range, the extra scope/bore distance won't matter at all.
I think your plan is absolutely fine. Just make sure to get a quality mount.
If you're going to be doing most of your shooting at exactly 300 yards (or close), then mount the scope and zero it for 300 yards.
For shorter shots, you'll have to compensate accordingly, but as long as you know the distance to your target, and the drop or rise (in this case, probably rise) of the bullet at that distance, you'll be fine.
The key is just getting a good trajectory chart for your gun and load with that particular sight mounting.
I don't happen to have one handy, though I think there are various ballistics programs that could make one for you, no problem. You might be able to find a 300 yard-zero ballistics chart for the gun online, and then just adapt it for your particular mount.
I think you'll find that with that setup the bullet will start out BELOW your sight line at short ranges, then rise above it, then drop down to hit it exactly at 300 yards. So you'll have a second "zero" at a shorter range (eg maybe around 50 yards. . .I don't know the exact distance).
With all do respect for Beantown----I have to disagree that the distance from bore to line of sight is not very important!!!
We aren't disagreeing.
I never said this "wasn't important"; I said just the opposite, that a big gap wasn't ideal, but that you could work with a 4" gap if you had to.
Of course for the reason you mention, its better to have the scope closer to the boreline if you can get it there. That's why "flattop" AR-15s exist.
However, in practice people mount scopes on the carry handles of AR-15s all the time, and they still get acceptable accuracy.
For further consideration, the iron sights on M16/AR-15 rifles sit right in that carry handle by design. They seem to work OK. Meanwhile the US Marine Corps uses a standard 300 yard battlefield zero (or at least they used to).
Whether or not this is the "best" battlefield zero is certainly debatable, but if the USMC does it that way, its probably safe to say that a carry handle line of sight can't be THAT horrible out to 300 yards. Putting a scope right on top of there should only raise the line of sight by maybe an inch or so.