PTR Industries PTR 91 A3SK .308 Win Carbine, 16 in Threaded Barrel, M-LOK Handguard, AR-15 6-Position Stock, HK91 Lower, Diopter Sights
This PTR Industries PTR 91 A3SK is a U.S.-made, roller-delayed blowback carbine chambered in .308 Winchester with compatibility for 7.62×51 NATO. It features a 16-inch threaded 4140 chrome-alloy steel barrel with a birdcage-style flash hider featuring a few long, teardrop-shaped side ports and a smooth, flat front (no crenellations), a factory diopter sight system, and a scope mount. This example stands out with an HK 91 lower installed, an HK parts M-LOK aluminum handguard, and an AR stock adapter fitted with a 6-position collapsible AR-15 pattern stock.
Condition
Overall Condition: Very good condition, showing only light, superficial signs of prior handling or use.
Bore Overall Condition: Excellent - Clean, mirror finish, no signs of wear.
Bore Rifling: Excellent Rifling - Sharp lands and grooves.
Specific Condition Details: The firearm presents in great shape overall. Minor superficial scratches and small blemishes are visible on close inspection.
What’s Included
- PTR Industries PTR 91 A3SK semi-automatic rifle
- 1x 20-round HK-marked G3 steel magazine
The A3SK carbine configuration uses a 16-inch barrel made from 4140 chrome-alloy steel and is threaded at the muzzle with a birdcage-style flash hider that has long, teardrop-shaped side ports and a smooth, flat front. The action is PTR’s proven semi-automatic, roller-delayed blowback system with a left-side charging handle and a dedicated HK slap position.
Upgrades include an HK parts M-LOK aluminum handguard for direct accessory attachment and an AR stock adapter fitted with an AR-15 pattern 6-position collapsible stock. The adjustable stock yields an approximate 13–16 inch length of pull, offering practical fit across positions.
This rifle is configured with an HK 91 lower installed, featuring the SEF-marked 3-position selector legend on the polymer housing. Sights are the classic HK pattern: a hooded front post and a rotary diopter rear drum with apertures indexed for 100–400 yards.
The receiver is constructed from 1018 sheet steel and is marked “PTR 91” and “PTR INDUSTRIES, INC., AYNOR, SC, U.S.A., .308 CAL.” A scope mount is present on the receiver. The serial number is located on top of the receiver forward of the ejection port.
Chambering accepts both .308 Winchester and 7.62×51 NATO. Capacity is 20+1, and the platform is compatible with HK G3/HK91 pattern magazines. One 20-round HK-marked G3 steel magazine is included.