The Luth-AR .308 builder lower parts kit is a set of small lower receiver parts for an AR-10 build (brand part no. LRPK-BLDR-308). It carries the parts that are specific to the .308 pattern, including the bolt catch, the bolt catch screw and the front pivot pin, alongside the detents, springs and pins every lower needs. Luth-AR says all of the parts in its lower parts kits are investment cast or otherwise machined to Mil-Spec drawings, materials and heat treat, and it states there is no MIM in them. The springs are a mix of 17-4 stainless and Mil-Spec steel wire, with certification. It suits a builder who is assembling a .308 lower and wants quality American-made hardware from Luth-AR.

Key Specifications

• The kit is made for .308 AR-10 lowers, so the bolt catch, catch screw and front pivot pin match that pattern.
• The kit includes a selector and safety, the control that locks the fire control group.
• The bolt catch group includes the bolt catch, spring, buffer plunger and screw, which hold the bolt open on an empty magazine.
• The magazine catch group includes the magazine catch, an aluminum catch button and a spring, which keep magazines seated and release them on demand.
• The kit includes a buffer retainer and retainer spring, the small parts that hold the buffer in the tube.
• Pins in the kit include a front pivot pin, a rear takedown pin and two hammer and trigger pins, which hold the upper and the fire control group in place.
• The kit has two detent springs and two takedown detents, which keep the takedown pins from walking out.
• The selector comes with a selector detent and a selector spring, which give the selector its positive click.
• The parts are investment cast or machined to Mil-Spec, with springs in 17-4 stainless or Mil-Spec steel wire and no MIM parts.

Frequently Asked Questions

Does this kit fit an AR-15 lower? No. It is the .308 kit for AR-10 pattern lowers, so use Luth-AR’s AR-15 builder kit for an AR-15 lower.

Is this a builder kit or a complete kit? It is the builder kit. The list covers the catches, springs, detents and pins, and Luth-AR sells separate triggers, grips and other parts for the rest of the build.

Where are Luth-AR parts made? Luth-AR describes its parts as American made.

Buy the Luth-AR Builder Lower Parts Kit for AR-10, .308

A lower is only as dependable as its small parts, and this kit gives a .308 builder good materials to start from. Order it from our Lubbock, Texas gun shop for fast shipping, and browse more AR lower parts kits while you are here.