do you find the aiming dots are necessary with only 3x magnification?
The multiple dots for different distances, you mean?
http://www.eotech-inc.com/product.php?id=8&cat=1
It really depends on how far you typically will be shooting. If almost all of your shooting is going to be at less than 400 meters/440 yards, the multi-dot reticle doesn't make much sense, since you use the top dot for those ranges anyway. Here's the iSnipe trajectory for a 55gr .223/5.56x45mm at 3000 ft/sec, ballistic coefficient 0.243, at 75 degrees Fahrenheit, zeroed at 50 yards for a 225-ish far zero:
Yards................Point of Impact
5 yards....................2.5" low (use the bottom of the ring to aim)
10 yards...................2.2" low (use the bottom of the ring to aim)
15 yards...................1.9" low
20 yards...................1.6" low
25 yards...................1.3" low
30 yards...................1.0" low
40 yards...................0.5" low
50 yards...................right on
75 yards...................1.0" high
100 yards..................1.7" high
125 yards..................2.1" high
150 yards..................2.2" high
175 yards..................1.9" high
200 yards..................1.2" high
225 yards..................0.1" high
250 yards..................1.5" low
275 yards..................3.5" low
300 yards..................6.0" low
350 yards.................12.8" low
400 yards.................22.2" low
450 yards.................34.7" low
500 yards.................50.7" low
550 yards.................70.9" low
600 yards.................96.1" low
650 yards................126.9" low
You can see that out to 275 yards, you're still within 3.5" of the line of sight, and out to 350 you're within a foot of the line of sight. Even at 400 yards, a couple feet of holdover isn't that hard to estimate. If you had a multi-dot reticle, you'd still be using the topmost dot at those distances.
Where the multi-dot reticle really shines is at 500+ yards. Depending on your zero, the bullet is 4 feet low at 500 yards, 8 feet low at 600 yards, and almost 11 feet low at 600 meters/656 yards. Judging that degree of holdover is tricky, so once you get out in the 500-600+ yard regime, the extra dots are useful.
For myself, I went with the single-dot-and-circle
Eotech 516, which is $90 to $150 cheaper than the multi-dot (but otherwise similar)
model 557. Finances were (and are) tight with me, and since I personally don't have much occasion to shoot beyond 400 yards, the single-dot was a pretty easy choice. It's also less busy for close-range shooting than the multi-dot reticle would be.
A note about model numbers and such. Eotechs come in two basic flavors: (1) those that are set up for a lower-1/3 cowitness right out of the box, and (2) those that are set up for an absolute cowitness out of the box and need an aftermarket 7mm riser to do a lower-1/3. Within each of those two categories, some models have the capability to go ultra-dim for use with night vision equipment, and some don't (with NV capability jacking up the price quite a bit).
The following models are set up for a lower-1/3 cowitness out of the box, thanks to a built-in 7mm riser: Eotech 516, 517, 553, 556, 557. As far as I know, all other models (including 512, XPS series, etc.) are set up for absolute cowitness, so if you want a lower 1/3 cowitness you'll need a 7mm riser, like a LaRue QD mount.
Battery requirements are as follows:
- 516: two CR123, 1000hr runtime at brightness 12 (longer at lower settings)
- 517: two AA, 600hr runtime at brightness 12 with alkaline, 1000hr with lithium
- 553 (similar to 516 but with NV setting and QD base): two CR123, 1100 hours runtime at brightness 12
- 556 (similar to 516 but with NV setting): two CR123, 1100 hours runtime at brightness 12
- 557 (similar to 517 but with NV setting and multi-dot reticle): two AA, 600hr runtime at brightness 12 with alkaline, 1000hr with lithium
I prefer CR123 because they are physically shorter and allow me to run the same battery type in my optic and light. They don't cost any more than AA lithiums and are available at my local Walmart just like AA, so I don't really see much logistics advantage in using AA's.
The XPS series all run off a single CR123 battery and are set up for absolute cowitness (they need a 7mm riser to do a lower 1/3). The designations are as follows:
- XPS2-0 single dot in circle (traditional Eotech reticle), no NV setting
- XPS2-1 single dot only (no circle), no NV setting
- XPS2-2 two dots in circle, no NV setting
- XPS3-0 single dot in circle (traditional Eotech reticle), NV setting
- XPS3-1 single dot only (no circle), NV setting
- XPS3-2 two dots in circle, NV setting
Aimpoint model designations are a bit easier to understand. Basically, the CompM series has rubber armor and night vision settings, the CompC series does not but is considerably cheaper, and the Micro is a scaled-down model for light weight and small size (Micro T-1 has NV capability, Micro H-1 does not). You can get various models with 2 MOA, 3 MOA, and 4 MOA dots (I prefer as small as possible). All Aimpoints will need a riser to mount properly; LaRue Tactical makes some of the best Aimpoint mounts, but there are other players in the market as well.