Primary Arms SLx 4.5-27x56 FFP

Precision / TacticalFFPMRAD34 mm tubeIlluminated

The Primary Arms SLx 4.5-27x56 FFP is a 4.5-27×56 FFP scope on a 34 mm tube with a ACSS Athena BPR MIL reticle, illuminated and 0.1 MRAD clicks. Across its range the exit pupil runs from an estimated 12.4 mm down to 2.1 mm at 27×, where the twilight factor is 38.9. At 33.2 oz it is 16th-lightest of the 26 precision scopes here, where the median is 31.4 oz.

Approx. price: ~$500
Magnification: 4.5-27×
Objective: 56 mm
Weight: 33.2 oz

Best for

Dialed shooting at known and unknown distances — PRS-style matches and long-range steel

Manufacturer’s product page — not an affiliate link. Price and availability there may differ from our snapshot.

Derived optics

estimated

Exit pupil: 12.4–2.1 mm (4.5×–27×)
Twilight factor: 38.9 at 27×
Zoom ratio: 6×

Exit pupil and twilight factor are computed from the published magnification and objective diameter, not measured. Real exit pupil is also capped by the erector at low magnification, and coatings and glass quality move low-light performance in ways the formula cannot see — read these as comparisons between layouts, not verdicts on scopes.

Specifications

Manufacturer-published figures, read from SUBSTITUTE for the discontinued SLx 5-25x56. primaryarms.com (SKU, price, tube, travel, Easy Stop, warranty) + ar15discounts.com listing (eye relief, FOV, length, weight); windage travel and parallax minimum not published. MOA/MRAD conversions use 3.438 MOA per mil.

Magnification: 4.5-27×
Objective lens: 56 mm
Focal plane: FFP
Reticle: ACSS Athena BPR MIL
Illuminated: Yes
Turret unit: MRAD
Per click: 0.1 MRAD (0.36″ at 100 yd)
Elevation travel: 32 MRAD (≈110 MOA)
Zero stop: Yes
Turrets: Exposed
Parallax: Side focus
Eye relief: 3.5″
Field of view: 23.4–4.1 ft at 100 yd
Tube: 34 mm
Length: 14.4″
Weight: 33.2 oz
Warranty: Lifetime

Features

FFP
MRAD
34 mm tube
Illuminated
Zero stop
Exposed turrets
Side focus
Lifetime warranty

For it, on paper

+ 32 MRAD of elevation travel in a 34mm tube, enough to dial well past 1,000 yd with most cartridges
+ FFP ACSS Athena BPR MIL grid is true at every magnification
+ Easy Stop zero return on the exposed elevation turret
+ 6x zoom ratio (4.5-27x) covers mid-range and extreme long range in one scope
+ Lifetime warranty at $500

Against it, on paper

− 33.2 oz and 14.4 in long, a bench and prone scope rather than a carry scope
− Only 3.5 in of eye relief with no published range, tight behind a hard-recoiling magnum
− 4.1 ft field of view at 27x makes finding targets at top power slow