The San Tan Tactical STT-15 Pillar ambidextrous billet receiver combo in Olive Drab Green (San Tan part no. STT15-COMBO-ANO-OD) pairs a billet upper and lower receiver machined from 7075 aluminum. San Tan Tactical built the STT-15 around a true ambidextrous AR-15 pattern layout, with controls that work for both right- and left-handed shooters. The upper adds M4 feed ramps, a shell deflector, a forward assist and an ejection port cover, while the lower brings an oversized trigger guard and a flared magazine well. It is a strong starting point for a custom 5.56/.223 build.

Key Specifications

• The receivers are machined from billet 7075-T651 aluminum, an aerospace-grade alloy known for strength.
• The finish is Mil-Spec MIL-A-8625 Type III hard anodizing in Olive Drab Green.
• The listed caliber is 5.56/.223, matching standard AR-15 builds.
• The set includes ambidextrous controls, so the manual of arms works from either side.
• The magazine well has a 1.38-inch integrally machined flare that guides magazines in during reloads.
• The upper includes M4 feed ramps and a shell deflector, matching common AR-15 barrel extensions.
• The forward assist is retained by a threaded dowel pin instead of a roll pin, and a mil-spec ejection port cover is included.
• The top rail is a Picatinny rail with T markings for easy optic relocation.
• The lower has an oversized winter trigger guard with room for gloved hands, plus a finger rest.
• The receivers are Made in the USA and carry a lifetime warranty from the maker.

Frequently Asked Questions

Are the controls ambidextrous? Yes. The Pillar set includes ambidextrous controls that allow the standard manual of arms from either the right or left side.

Which magazines does it use? The Pillar is compatible with STANAG pattern M16 and AR-15 magazines.

Will standard AR-15 parts fit? San Tan Tactical states that it works with mil-spec AR-15 and M16 components, except for its proprietary ambidextrous controls.

Buy the San Tan Tactical STT-15 Pillar Ambidextrous Billet Receiver Combo, Olive Drab Green

This billet combo is a clean foundation for a custom AR-15 with ambidextrous controls built in. Order it from our Lubbock, Texas gun shop for fast, insured shipping to your FFL, and see more AR-15 lowers on the site.