alfred10 said:
Whats the accuracy difference at 100 yards between the Aimpoint Comp M4 and Eotech? I thought the Eotech was more accuret than the aimpoint? Will the Aimpoint and regular eotech with a single dot shoot point of aim?
I think you're missing something here. A rifle can have a measured accuracy with a specific round. A person can be said to have a certain accuracy to their shooting. An optic doesn't have any accuracy itself, as it has nothing to do with the physics of how a bullet reaches the target.
Accuracy is commonly measured in Minutes of Angle (MOA), which is aprox 1" at 100 yards. If an optic has a 1 MOA aiming dot, the dot will cover an area 1" wide at 100 yards, a 2" area at 200 yards etc. If it has a 4 MOA dot, the dot will cover an area 4" wide at 100 yards, 8" area at 200 yards, etc. This does not denote accuracy though, it is simply the size of the aiming dot.
Now many shooters may find that they shoot more accurately with a 1 MOA dot that a 4 MOA dot, because it's easier to put the target directly behind the smaller dot than trying to center it behind a larger dot. However, everything else being the same, with a rifle zeroed at the distance being shot, your rounds will place directly behind the center of the aiming dot, regardless of it's size.
There are also many shooters that find it more difficult to rapidly acquire targets with a 1 MOA dot than a 4 MOA dot, because of it's smaller size, and the eye/mind having to work a little harder to build the sight picture. Eotech has compensated for this by providing a 65 MOA circle around the center aiming dot, allowing for faster target acquisition with a smaller dot. Again though, this has nothing to do with 'accuracy' of the optic, but rather how easy it is for the shooter to rapidly acquire a sight picture.
A loose definition of accuracy can be defined as the expected size of a group at a given distance. Note that accuracy is non-linear with distance. If a rifle can shoot 1" groups at 100 yards, that doesn't indicate that it will shoot 5" groups at 500 yards. The reason is that as a bullet decelerates, especially at the point where it goes sub-sonic, and as it's rotation slows, the size of the group will open up. A rifle that shoots 1" groups at 100 yards may shoot 7" groups at 500 yards, etc.
Another thing I think you are missing is that an optic is zeroed for a given distance. You can think of it this way - the bullets starts out low, and travels upward, crossing your point of aim at your zero distance, then continues traveling upward in an arc until it starts to fall, then crosses through your point of aim again, and then continues falling until it hits the ground. In reality the bullet doesn't actually travel upwards (it's always falling from the moment it leaves the barrel), whats happening is that the optic is looking at a downward angle through the bullet path, but it's easier to comprehend if you think of the bullet shooting at an upward angle.
Generally, you want to select a zero distance that will provide the least amount of vertical variation at the ranges you expect to shoot. Generally, with a 5.56/223 round that distance is 50 yards, and you should never be more than +/-2.5" out to several hundred yards.
If you absolutely need point of aim to equal point of impact for a given distance, you can get a ballistic calculator that factors in the the muzzle velocity of a given round from a given rifle, the bullet weight, ballistics coefficient, air density, temperature, humidity, the height of the sight above the bore, wind speed and direction, rotation of the earth, etc, and can calculate how many clicks you need to adjust your optic from where it's zeroed.
There's a lot of info out there that you should make yourself familiar with. You don't need to become an expert, but should understand the basics before jumping into spending several thousand dollars on a building an SBR.
