Magnification clarification..

[pgatour]

Hi, just finished a new AR-15 build and I'm looking to add either a scope or holographic/red dot sight.

I will mainly just be target shooting at 50-100yds, maybe 200 in the future.

My question, does a 1x magnification really allow you to see a 4" bulls-eye at 100yds? At 50 yds, the 4" bulls-eye takes up the entire 'pin hole' on a standard rear MI flip-up sight, so it was difficult to zero in on the 'exact' center (yes, let's assume 20/20 vision). Since I've never peered thru anything else before, I'm wondering if the popular EOTechs with 1x magnification will have enough magnification to see at 100yds (without a magnifier), or if I should consider scopes (looking at the Bushnell Banner series) that are 3x9x40.

Just trying to get an idea the difference between 1x holographic/red dot devices vs. 3x9x40 scopes and what that really translates to on the range in terms of being able to see pin-point targets at 50 yds..100yds. Much appreciate your feedback and experience.

[What Just Happened?]

+1. I'm also curious as I'm completely new to longarms.

[ocabj]

I have no idea what the size of the aperture is on an MI rear flip-up sight, but I can't imagine it's any smaller than a traditional NM rear sight aperture which is usually at .042" give or take.

A 4" black circle at 50 yards should never fill up the aperture with the correct cheek weld. You've got your head back too far on the stock or you have your rear sight too far forward.

[maxicon]

MI makes 2 rear sights now - their older ERS, and the new low profile SPLP.

The ERS uses the standard A2 apertures, which are 0.200 and 0.070 (the NM is smaller, as ocabj said). They don't spec the SPLP, but I'd bet they're the same.

Your aperture forms a part of a circle with your eye at the center. Any circle is 360 degrees * 60 minutes or 21,600 minutes.

To figure out what your aperture size translates to in MOA, you need to do this:

- Measure the distance between your eye and the sight aperture. Call this R.
- Calculate the circumference of the circle your aperture sits on, which will be 2 * 3.14 * D. Call this C.
- Divide the diameter of the aperture you're using (either 0.2 or 0.07 if you're using A2 apertures) by C. This is what portion of the circle your aperture takes up.
- Multiply that by 21,600 to get the MOA of your sight.

So, if you've got an A2 small aperture 10 inches ahead of your eye:
21,600 * (0.07 / (2 * 3.14 * 10)) = 24 MOA. The 0.2" aperture would give you 69 MOA.

As ocabj says, it would take a large distance from eye to rear aperture to make this obscure an 8 MOA target - roughly 30 inches.

For the other part of the question, I can shoot fine out to 100 yards with a red dot, Eotech, or iron sights, but not get very good groups with my aging eyes. If I want to get tight groups, or measure the capability of my rifle, I need a scope, and I prefer 9x-12x for 100 yards. Even 4x isn't good for me for tight groups, though it does tighten them a lot over iron sights.

Other people can get 1 MOA with iron sights, just not me.

For an inexpensive scope, I'd look at Millett, the Mueller APV, or Weaver, rather than a low-end Bushnell. The better Bushnells are fine (3200 and above), but the low-end ones are a mixed bag.

[pgatour]

...For an inexpensive scope, I'd look at Millett, the Mueller APV, or Weaver, rather than a low-end Bushnell. The better Bushnells are fine (3200 and above), but the low-end ones are a mixed bag.

Thanks Maxicon, I'll try the calculations you suggested. I'll see what I can find from the list you provided. I have the standard MI rear flip up sight, and from reading this forum I think my technique was wayyy off so that was a huge part of my problem. I'm going to try again this weekend with some of the tips I learned this week, and see if I get better results.