The UTG PRO AR-15 Ops Ready S4 Mil-Spec Stock Kit in black from Leapers (brand part no. RBUS4BM) is a complete four-position stock set for an AR-15, molded from impact-resistant polymer in a minimal-bulk profile. The kit includes the mil-spec extension tube, buffer, buffer spring, receiver end plate and castle nut, so the stock and the hardware behind it arrive together. A slanted cheek rest and a rubberized butt pad make shouldering easier, and a removable 5.51-inch extended cheek rest insert is included. The stock has a reversible sling swivel housing for left- or right-handed setups and a standard sling loop for traditional slings. It is designed and made in the USA, with a compact length of pull that stays comfortable when you are wearing a vest or plate carrier.

Key Specifications

• The kit includes a mil-spec extension tube, a standard carbine buffer (3.0 ounces), buffer spring, receiver end plate and castle nut, so the stock mounts with the hardware behind it.
• The stock has four positions of adjustment, moving in 0.625-inch increments with a mil-spec carbine extension tube.
• Length of pull runs from 10.2 inches collapsed to 11.5 inches extended, measured with a mil-spec carbine extension tube.
• Materials are polymer and aluminum, with the stock molded from impact-resistant matte black polymer.
• A slanted cheek rest and rubberized butt pad come on the stock, with a removable 5.51-inch extended cheek rest insert included.
• A reversible sling swivel housing works for left- or right-handed shooters, and a standard sling loop is built in for traditional slings.
• The kit weighs 15.5 ounces, as listed by UTG.

Frequently Asked Questions

What comes in the stock kit? The kit includes the stock, a mil-spec extension tube, a buffer, a buffer spring, a receiver end plate and a castle nut, plus a removable 5.51-inch extended cheek rest insert.

Will the kit fit my AR-15? It is listed as compatible with the AR-15 and ships with a mil-spec extension tube, so it is built for standard AR-15 lowers.

Can I switch the sling attachment for left-handed use? Yes. The stock has a reversible sling swivel housing for left- or right-handed shooters, plus a standard sling loop.

Buy the UTG PRO AR-15 Ops Ready S4 Mil-Spec Stock Kit, Black

Buying the stock and the tube hardware as one kit removes the guesswork from a compact AR-15 build. Order it from our Lubbock, Texas gun shop for fast, insured shipping, and browse more rifle stocks while you are here.