What magnification for scoped ar15

[xd40]

[Tommy Gun]

3x9 40mm on the low end and 4x14 44mm or 50mm on the higher end. You could get away with a 1x6 or 8 if you know what you are doing. 1x good if you also want close range as well. Or go with offset irons along with scope.

[xd40]

3x9 40mm on the low end and 4x14 44mm or 50mm on the higher end. You could get away with a 1x6 or 8 if you know what you are doing. 1x good if you also want close range as well. Or go with offset irons along with scope.

Thanks for the reply. I definitely plan on doing offset irons.

Stupid question - the mm (eg. 40mm or 50mm) refers to the size of the scope housing correct? But how does it effect the range or usability of the optic?

thanks

[kcheung2]

The "40" in a 3-9x40 refers to the size of the objective lens. It approximately corresponds to the size of the bell but is not an exact match because the lens must be smaller than the bell housing it. (kinda like how a 50" tv isn't exactly 50", it's more like 49.4" or somesuch) Generally if all factors are equal, the larger the objective lens, the better the light-gathering ability & thus a brighter image. However, all factors are rarely equal & glass quality trumps all. So a smaller but higher quality lens, even though it's paper specs may seem inferior, would be brighter than a cheapy scope with terrific sounding numbers.

What you might be thinking about when you say scope housing is possibly the tube diameter, which is the narrow middle portion of the scope. It is usually 1 inch (25mm) or 30mm, and on some high end scopes it is 34mm. A larger number allows for greater elevation adjustments, so for example a 25mm tube only allows for a total of 80moa in adjustment from bottom to top, but a 30mm allows for 100moa. (Those are hypothetical numbers, not based on any specific scope)

[xd40]

The "40" in a 3-9x40 refers to the size of the objective lens. It approximately corresponds to the size of the bell but is not an exact match because the lens must be smaller than the bell housing it. (kinda like how a 50" tv isn't exactly 50", it's more like 49.4" or somesuch)

What you might be thinking about when you say scope housing is possibly the tube diameter, which is the narrow middle portion of the scope. It is usually 1 inch (25mm) or 30mm, and on some high end scopes it is 34mm.

that makes more sense. thanks!

[Tere_Hanges]

Read this

https://www.targettamers.com/guides/rifle-scope-objective-lens-diameter/

[Tommy Gun]

30mm tube is mainly standard for most scopes. I got 34mm Burris 5x25 50 for better elevation adjustments and Field of View at higher magnification. For your application 30mm is all you need. Since its shorter distance cantilever mount will be sturdy. Hight of the mounts will have to be subjective. This is where cheek risers come into play if you so choose. I'd get a higher magnification scope just so at 600 yds you can actually see the target and not try to aim at a spec in your field of vision. 14x ish mag is good enough, will be cheaper generally speaking.

Then comes what you want out of it which will narrow your options. First Focal Plane is more expensive but your "zero"will remain the same no matter your magnification. Second Focal Plane generally only holds zero at the magnification you zero it at, meaning if you zero at say 9 power of a 14 power scope your projectile will not track the same as it would at 9 power. Not a big deal if shooting 100 yds or even 200 yds, but out to 600 yards you could be talking feet off target.

[OpticsPlanet]

2.5-10x or 3-12x are the scopes i would be looking at.

If you can provide a budget, people can make specific recommendations.

-Matt S.

[xd40]

Read this
https://www.targettamers.com/guides/...lens-diameter/

very helpful, thank you!

[xd40]

2.5-10x or 3-12x are the scopes i would be looking at.

If you can provide a budget, people can make specific recommendations.

-Matt S.

considering the Vortex Crossfire II 4-16x50 AO. seems to be well rounded and id like to be in that $350ish range

[NorCalFocus]

considering the Vortex Crossfire II 4-16x50 AO. seems to be well rounded and id like to be in that $350ish range

Its okay, but the turrets are going to be a PITA to turn up and down, and the BDC isn't going to be very helpful in making longer range hits. Plus I don't think your gaining much with that 50mm bell on a 18" AR.

AO or side paralax adjustment is a huge benefit. Side adjustment knobs are much easier to use however. For high end magnafication on your build I like the 16-20 range. I personally use a 6-20 on my AR, which allows me to focus better on small targets like squirels at 400 yards.

-Diamondback Tactical has target turrets which will make adjustments easier, and a very useful reticle for wind and hold overs. The lack of paralax adjustment is the only thing I don't like.

https://www.opticsplanet.com/vortex-diamondback-tactical-4-12x40-riflescope.html

-The Strike Eagle 3-18 is really what I would consider ideal for your build. I think it has all the features one needs, and a good zoom range. Its $100 over your stated budget though. But if you can afford it, you wouldn't be disaponted.

https://www.opticsplanet.com/vortex-strike-eagle-3-18x44-riflescope-w-ebr-4-moa.html

-Primary Arms 4-14 MOA scope also intrigues me too. Its a lot of features for the money. I've been considering one for my next build.

http://www.primaryarms.com/primary-arms-4-14x44mm-ffp-riflescope-arc-2-moa-reticle

[xd40]

Its okay, but the turrets are going to be a PITA to turn up and down, and the BDC isn't going to be very helpful in making longer range hits. Plus I don't think your gaining much with that 50mm bell on a 18" AR.

AO or side paralax adjustment is a huge benefit. Side adjustment knobs are much easier to use however. For high end magnafication on your build I like the 16-20 range. I personally use a 6-20 on my AR, which allows me to focus better on small targets like squirels at 400 yards.

-Diamondback Tactical has target turrets which will make adjustments easier, and a very useful reticle for wind and hold overs. The lack of paralax adjustment is the only thing I don't like.

https://www.opticsplanet.com/vortex-diamondback-tactical-4-12x40-riflescope.html

-The Strike Eagle 3-18 is really what I would consider ideal for your build. I think it has all the features one needs, and a good zoom range. Its $100 over your stated budget though. But if you can afford it, you wouldn't be disaponted.

https://www.opticsplanet.com/vortex-strike-eagle-3-18x44-riflescope-w-ebr-4-moa.html

-Primary Arms 4-14 MOA scope also intrigues me too. Its a lot of features for the money. I've been considering one for my next build.
http://www.primaryarms.com/primary-a...-2-moa-reticle

Damn that primary arms one has a lot going on for the price, might be worth a try. Thanks for the input!

[smoothy8500]

Second Focal Plane generally only holds zero at the magnification you zero it at, meaning if you zero at say 9 power of a 14 power scope your projectile will not track the same as it would at 9 power. Not a big deal if shooting 100 yds or even 200 yds, but out to 600 yards you could be talking feet off target.

What cheap scope are you using that can't hold zero and hits "feet off target"?

[NorCalFocus]

Then comes what you want out of it which will narrow your options. First Focal Plane is more expensive but your "zero"will remain the same no matter your magnification. Second Focal Plane generally only holds zero at the magnification you zero it at, meaning if you zero at say 9 power of a 14 power scope your projectile will not track the same as it would at 9 power. Not a big deal if shooting 100 yds or even 200 yds, but out to 600 yards you could be talking feet off target.

A scope holding zero has nothing to do with it being a second focal plane vs a first.

What changes is the value of your hashes or reticle. On a second focal plane scope your reticles value are only true at one power magnification, usually the highest. So if your trying to range a target or hold off you can only do that accurately at the one power setting.

[jimmykan]

My advice for a "long range" AR is to not over-do the magnification, unless it is JUST for shooting tiny groups on paper targets.

Here is my rule of thumb:

To shoot a target accurately you need to see it clearly enough, and to me "enough" means you can identify or resolve the outline of the target from its surroundings and find the apparent center. You don't need to see every single detail of the target in Ultra HD 4K in order to take a shot in confidence.

My vision is not 20/20 but I do not need glasses. I can see with naked eye the 6-inch diameter aiming black of an NRA 100-yard rifle target from 100 yards clearly enough to take a shot.

For every 100 yards I add to the target distance while keeping the actual size of the target at 6 inches, then I need to add 1X of magnification to maintain this level of clarity.

So in other words:

6-inch target @ 100 yards: 1X minimum magnification
6-inch target @ 200 yards: 2X minimum magnification
6-inch target @ 300 yards: 3X minimum magnification
...
6-inch target @ 600 yards: 6X minimum magnification

Keep in mind that if the target's actual size grows proportional to the target distance, such that the apparent size of the target stays the same with respect to my sights or reticle, then the required magnification also stays the same. For example, the aiming black of the NRA 600-yard target is 36 inches in diameter, and this is meant to be shot using iron sights.

6-inch target @ 100 yards: 1X minimum magnification
12-inch target @ 200 yards: 1X minimum magnification
18-inch target @ 300 yards: 1X minimum magnification
...
36-inch target @ 600 yards: 1X minimum magnification

Now if I am trying to spot my bullet holes from my shooting position using the rifle scope, and they are small .22 caliber holes on regular paper, not shoot-n-see splatter targets, then I need about 16X per 100 yards distance, if the glass quality is average, like a Vortex Viper PST. If I am looking through really clear glass, then I can see .22 caliber holes from 100 yards with 10X or 12X magnification.