An affordable, ballistically-matched optic for your AR-10

If you own an AR-10 style rifle chambered in .308 Win. (7.62 NATO), the new P-308 4-12×40 BDC 800 riflescope ($249.95) could be exactly the optic you’re looking for. Simply put, the P-308 4-12x40mm BDC 800 is a lower magnification version of the company’s M-308 4-16×42 BDC 800 ($499.95), with a slightly smaller objective lens (40mm vs. 42mm) and fewer features, but at half the price.

The P-308s BDC 800 reticle was designed for precise bullet-dropcompensation of 168-gr. .308 Win.
The P-308s BDC 800 reticle was designed for precise bullet-dropcompensation of 168-gr. .308 Win.

Built on a 1-inch diameter tube machined from aerospace-grade aluminum alloy, the P-308 offers a 40mm objective lens and a 4- to 12-power magnification range. A big, easy to use, rubber covered zoom ring is located just forward of the ocular lens, which includes a rubber covered focus ring with unspecified (but ample) diopter adjustment.

The P-308 is equipped with Nikon’s popular BDC 800 reticle—a reticle that was specifically engineered for bullet drop compensation with the .308 Winchester/7.62x51mm NATO round loaded with 168-grain hollow-point, boat-tail Match bullets with a muzzle velocity of 2,680 f.p.s. When sighted in at 100 yards, alternating black and clear dots on the lower vertical stadia line indicate hold-over points for this round at ranged out to 800 yards. Short horizontal lines between the dots indicate 50 yard increments from 150 to 750 yards. There are no windage offset marks on the horizontal stadia lines.

Nikon MainThe P-308 is optimized for use with Nikon’s Spot On Ballistic Match Technology. The Spot On program provides users with the exact aiming points on any BDC reticle for any load or ammunition at a specific range. The Spot On program is free online at nikonsportoptics.com/SpotOn, and is now free as an app for mobile devices, including the iPad, iPhone and Android platforms.

The spot on program -free online at nikonsportsoptics.com;-provides exact aiming
The spot on program -free online at nikonsportsoptics.com;-provides exact aiming

The P-308 lacks the parallax adjustment dial of its more expensive cousin (parallax is zeroed at a fixed range of 100 yards), but does include the same raised, spring-loaded Instant Zero-Reset Turrets with easy-to-grip, coarsely knurled top rings, which make in-field adjustment easier by allowing shooters to reset their turrets back to zero after sighting in. All you have to do is sight in as usual, then lift the spring-loaded adjustment knobs, rotate them to your “zero” and re-engage. Field adjustments are now as simple as dialing in your target’s range and best guess at “Kentucky windage.” Positive click adjustments move the point of impact 1/4” at 100 yards (1.0” at 400 yards; 2.0” at 800 yards).

We used an ADM 1-piece QD auto lock mount (americandefensemfg.com) throughout testing.
We used an ADM 1-piece QD auto lock mount (americandefensemfg.com) throughout testing.

The scope’s fully multi-coated optical system has multiple layers of anti-reflective compounds on every glass surface to provide bright, clear sight pictures and optimum light transmission from dawn to dusk. It is also fully waterproof, fog proof and shockproof. Other vital statistics include exit pupil diameter of 3.3mm to 10mm (depending on magnification setting), and a field of view at 100 yards of 23.6 feet at 4x and 7.9 feet at 12x magnification. The ocular lens outside diameter is 44mm, it weighs 17.5 oz. and measures 13.5 inches in overall length. Maximum internal adjustment range is 60 MOA in both axes.

A rubber-armored magnification power ring runs from 4 to 14x.
A rubber-armored magnification power ring runs from 4 to 14x.

For testing we mounted the P-308 scope in our trusted American Defense Manufacturing AD-RECON one-piece, Q.D. mount and attached it to the optics rail of a Les Baer .308 Monolith SWAT model with 20-inch barrel. This rifle won a 2011 Editors’ Choice Award by shooting a record smallest group of 0.23 inch at 100 yards using Black Hills 168-gr., hollow-point, boat-tail Match ammo with a muzzle velocity of 2,650 f.p.s.

We zeroed the P-308 at 100 yards using the same Black Hills 168-gr., hollow-point, boat-tail Match ammo, and then moved the range out to 600 yards, which was the longest range available to us for this testing session. At 600 yards the point of impact averaged about 2.5 inches below point of aim using the P-308’s 600-yard dot—a difference that we attribute 100% to the 30 foot per second slower starting velocity of the Black Hills round compared to the 2,680 f.p.s. starting velocity Nikon used to calibrate the BDC 800 reticle.

Point info for any cartridge.
Point info for any cartridge.

Like all Nikon riflescopes, the P-308 is backed by Nikon’s Limited Lifetime Warranty and No-Fault Repair/Replacement Policy. This is one heck of a long-range riflescope for the money. See it at your gun shop, or for more information contact Nikon Sport Optics, Dept. OT; Tel.: (800) 645-6687; Web: www.nikonsportoptics.com