There are better for less. - San Tan Tactical STT-15 Pillar Billet Upper Receiver

It’s all 3 of the 3 stars but can never be a 4 or 5. It’s also a one a two as well as three stars. Knowing what I know now, would I order the SanTan Pillar Billet upper again? No. Would I recommend it? Yes. It’s still a must have and must see. The VLtor MUR is a much better buy at $25-$50 lower. I only wanted one San Tan upper to begin with. Seemingly well planned and executed design. It matched the Radian adac lower well enough as I’d expect from two different brands. The patterned cuts look great. The larger bolt catch of the Radian is more angular and looks good on the oval shaped depression of the San Tan Upper. Very solid and stiff Upper around the bolt cam.

On the top left, the upper scratched the finish off two brand new Radian raptor CH’s (one standard and the other a SD). I installed the Geissele Super CH and it works. No scratch. Tolerance stacking? I cannot be completely sure; I believe the tighter tolerance helps with the gasses to the face. I can’t be completely sure because this is my 1st Geissele CH and they get great reviews on the gas to the face issues.

It comes with a milspec FA. I have a dimpled grip San Tan forward assist. It over-rotates roughly 30 degrees and requires a larger dia. threaded pin. Contact San Tan. Stick with the stock milspec fa and all is well.

The cuts are just a bit too sharp. I’m no wizard but I don’t see how radiuses would hinder the strength or stiffness in it’s skeletonized design. Not an issue with gloves. Actually great grip. Might increase the cost some if the edges were slightly beveled.

I changed out the stock ejection port cover to a MagPul polymer EPC. The stock cover scratched the finish off the new Radian lower at the range. The steel angled plate on the outside of the port cover was really rough but it was the loose fit that made the scratch worse. The rough edges of the port door ran back and forth over the edge on the beefed up portion of the lower. I’m a poly ejection port cover fan since.

The barrel fit was tight required much less heat than a BCM upper. The barrel is a Spikes Tactical Optimal 5.56 FN CHF MID. 26. something oz.

Rubber City Armory Bolt Carrier.
Head spaced ST NiB Bolt. RCA hardware.