STT PILLAR Billet Upper Receiver with Forward Assist

With so many AR-15 upper receivers on the market today, we decided to challenge ourselves and create something better, something different. Being better was not enough — we needed to design an upper that overcame the shortcomings we saw in current offerings. It needed to be lighter, stronger, and distinctive, all while looking good doing it. We weren’t going to settle for just hacking another receiver out of a block and calling it done.



Our approach to the AR-15 upper receiver is that it needs to stand out from the crowd of existing offerings while offering improvements and features not seen elsewhere. Our upper needed to be lighter, stronger, and different, and have the looks to turn heads. Our receiver truss pockets are usually the first thing people see. These distinctive trusses help to bolster the integrity of the receiver and give the functional style our customers demand. 

The STT-15 comes standard with M4 feed ramps and shell deflector. Our forward assists are retained by a threaded dowel pin to eliminate the use of a roll pin, and come with a milspec ejection port cover. The top picatinny rail features machined in T markings for easy optic relocation. 

When most people think of a billet receiver they think of a blocky, heavy, thick design that is CNC machined. We wanted to break that pattern. Our receivers are Cut from a single billet 7075 -T651 aerospace grade aluminum. Thru the use of 3D CAD modeling software, we were able to save weight in places that extra material didn’t have a purpose, such as the forward assist block and the shell deflector. These spots are often very bulky on other billet sets due to the difficulty of removing material on all of those angles. After all of was said and done the new STT upper receiver came in at only 8.2 ounces. 


  • – Huge 1.38” Integrally Machined Magazine Well Flare
  • – Ambidextrous Quick Attach \Detach Sling Swivel Points With Anti-Rotation Stops Every 45 Degrees.
  • – Ambidextrous Bolt Release.
  • – Ambidextrous Magazine Release.
  • – Bullet Pictogram Safety Selector Markings.
  • – Set Screw Trigger Creep Adjustment.
  • – Set Screw Upper Take Down Tension Adjustment.
  • – Shooter Ready Finger Rest.
  • – Oversized Winter Trigger Guard.
  • – Dowel Screw Assembly.
  • – Ultra Grip Texture On All Controls.


  • Model: STT-15 
  • Caliber:  5.56 NATO \ .223 REM, 300 BLACKOUT, 22LR, Multi-Cal
  • Action: Semi-Auto
  • Weight: 9.4 Ounces With Ambidextrous Controls 8.4 Ounces Without Ambidextrous Controls.
  • Dimensions: Length: 7.69” Width: 1.490” Height: 4.015”
  • Material: Billet 7075-T651 Aerospace Grade Aluminum, Cast A-2 Tool Steel
  • Finish: Aluminum – Matte Black MIL-A-8625 Type III Hard Anodize, Steel – Black Oxide
  • Butt-Stock: Works With Any Mil-Spec or Commercial Buffer Tube and Stock.
  • Magazine Compatibility: The Pillar is compatible with all STANAG pattern M16/AR15 magazines.
  • Component Compatibility: Works With All Mil-Spec AR-15\M16 Components*.

*Excluding proprietary ambidextrous controls.



Santan Tactical
Direct: 480-726-8261
Fax: 480-393-4018
Mailing Address:
2223 West Pecos Road
Suite #6
Chandler, AZ 85224