Many shooters think compact sights can’t offer bright images. Wrong. Image quality – sharpness as well as brightness – depends mainly on the lenses and their coatings. In normal light, your eye’s pupil contracts.
If a scope’s exit pupil (objective diameter / magnification) is larger than your eye’s pupil, you can’t use all the light coming through the sight. Only in dim conditions does big front glass help at all.
For most big game hunting I favor 4x magnification. The 32- to 40mm objectives common to the 4x provide 8 to 10mm of exit pupil – more than your eye can use even in total darkness. A 6×36 scope delivers a shaft of light big enough for any shooting conditions.
Want more power? Well, probably you don’t, at least for deer and elk. If you’re shooting small animals at distance, you may benefit from higher magnification. But you needn’t endure scopes with maws the size of motorcycle mufflers. A 3mm exit pupil suffices for Dogtown – as in a 14x scope with a 42mm objective.
For big game, the long-popular 3-9×40 is still a top choice. And as competition in this slot is brisk indeed, you’ll find bargains at every price point. My latest rifle, a .25-06 by talented gunmaker Patrick Holehan, wears a 3-10×42 Swarovski, about as big a scope as seems appropriate. I’d have been as pleased with a 3-9×36, or Leupold’s 2.5-8×36.
Another concern when choosing a scope is free tube – space available for rings. In days of yore this was no issue at all, because scopes were of fixed magnification and had tubes as long as a swimsuit model’s legs.
Now scopes are short-coupled, with big turrets and power-selector rings that take up lots of tube. You’re wise to consider where the scope must sit on the rifle to give you proper eye relief.
Some scopes now are AR-specific, following the market to rifles with a mean look and no soul. The high line of sight mandated by the high comb of ARs, and the full-length Picatinny rail standard on models intended for scope use give you more options that do bolt- or lever-action rifles. Rails give even short-coupled scopes plenty of latitude fore and aft.
Leupold catalogs several sights specifically for the AR, from the CQ/T 1-3×14 scope to a 1×14 Prismatic sight to the new DeltaPoint reflex red-dot sight with magnesium housing. I have a Mark AR 3-9×40 on an AR in 6.8 SPC.
No, I’m not categorically opposed to big scopes. Or to liberal politicians or people who drive 55 in the left-hand lane. But sights should not over-burden rifles. And if your rifle’s sight accounts for more than 15 percent of its overall weight, you might ask yourself: Do I really need all that glass?
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