// Receivers
Uppers and lowers, built like our rifles.
The same complete upper and lower receiver groups our firearms are built from — assembled, gauged and checked to the same standard, and sold on their own.
// Two groups
Choose your half
// Upper Receiver Groups
Complete Uppers
Small-frame SOTM4 uppers on the HM Defense Monobloc® barrel — the forged SOTM4 MOD-0 thermal fitted to the barrel, or SOTM4 Billet with a bedded barrel extension — and large-frame SOTM5 Billet uppers for full-power cartridges. Every one ships with the SOT Enhanced HMB™ bolt carrier group.
- 5.56 NATO
- 6mm ARC
- 6mm MAX
- .308
- 6.5 Creedmoor
- 8.6 Blackout
// Lower Receiver Groups
Complete Lowers
The SOTM4MOD1 A5 forged lower from our SOTM4A5 Forged Series rifles, sold complete: Schmid Inside Elite two-stage DLC trigger, Geissele Ambi Posi-Snap selector and Maritime bolt catch, SOT A5 nine-position buffer tube with an A5H2 buffer, and a B5 Systems Bravo stock and Type 23 grip. Fits any Mil-Spec AR-15 upper.
- SOTM4MOD1 A5 forged
- Schmid 2-stage DLC
- A5 nine-position
- FDE or black
- $625.00
ARROW-INDEXED CAM PIN
On every complete upper — always installed the same direction, for consistent wear and longer cam pin life.
LASER-ENGRAVED CALIBER
Inside and outside the ejection port cover, so the caliber can be confirmed visually in an instant.
TWO-STAGE + A5
Every complete lower carries a two-stage trigger and the A5 recoil system — the same set-up as our rifles.
// How they ship
One ships to you. One ships to your dealer.
Complete uppers ship direct
A complete upper is not a firearm, so it ships straight to you. We do not ship AR-15 upper receivers, conversion kits or barrel assemblies to CA, CT, DE, DC, HI, IL, MD, MA, NJ, NY, RI or WA, or to certain localities including Denver, CO and Cook County, IL. Exception: Monobloc uppers are marked and marketed as HBAR and can ship to Maryland.
Complete lowers ship to your FFL
The lower receiver is the serialized part, so a complete lower is a firearm. It ships to your FFL dealer for transfer, never direct — you choose the dealer at checkout. We do not ship complete lowers to CA, CT, DE, DC, IL, MD, MA, NJ, NY, RI or WA.
Questions? Consult your local FFL, or ask our support team. Want the whole rifle instead? See Firearms. Individual upper and lower parts are on Parts.
WARNING: These products can expose you to chemicals including lead, which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.
Monobloc® and HMB™ are marks of HM Defense, LLC, used under license. Other product names are marks of their respective owners.
Bombproof by Design™
Precision // Purpose // Performance