I don’t keep up with Palmetto State Armory all that much. Not because I dislike them, but because they release so much stuff I can’t keep up. I see the emails all the time, and I check the Daily Deals page pretty constantly, but I only read the subject lines. One that stood out recently was “H&R DOE .300 Blackout has arrived.”
That blew my mind. I’m a huge fan of the H&R retro rifles and large-format pistols, and I absolutely love the H&R DOE guns. I’ve wanted a DOE gun since I flipped through an encyclopedia of guns as a kid and ran across it. The thing also captured my imagination, and PSA’s brand H&R released a replica pistol that I have and love.
The PSA and H&R DOE SMG
History of the DOE SMG
DOE stands for Department of Energy. Colt never officially called the DOE SMG the DOE SMG. Instead, it’s just the Colt Model 633. It’s a part of the Colt SMG family and a fairly unique part. It’s known for being extremely small, especially for the era. The distinct handguard and folding front sight make it distinct in the Colt SMG family.
Colt employees called it the “briefcase gun” because it fits inside a briefcase. It was remarkably small. One of the few purchasers and the most famous purchaser of the Colt Model 633 was the Department of Energy. Their compact design likely made them handy for vehicle use when transporting nuclear materials or patrolling a nuclear site in a vehicle.
Colt never released a civilian version of the DOE SMG, and replicas on the civilian market were rare, small-batch, and expensive. PSA and H&R made my dream of owning one possible. I love my little H&R DOE SMG, and it’s my favorite gun of 2025.
Seeing any new DOE SMG news gets me excited.
The DOE SMG Reimagined
.300 Blackout didn’t exist in the 1980s. If you wanted an uber-short and effective platform, you were using an SMG, namely a 9mm SMG. That’s not the case in 2025. The .300 Blackout cartridge premiered with the idea of creating an AR-compatible cartridge that could be shoved in an SMG-sized platform.
The .300 Blackout specifically focused on making a suppressible platform roughly the size of an MP5SD, while being roughly the same size. The DOE SMG with a seven-inch barrel would work well with .300 Blackout, a cartridge that reaches peak velocity out of a 9-inch barrel.
If you were to make a modern DOE SMG, then .300 Blackout would be your go-to cartridge. There are piles of AR pistols with short barrels in .300 Blackout; that’s not new. PSA and H&R created an uber-short AR pistol with the design aesthetics and features of the DOE SMG, but in a much more capable cartridge.
The .300 Blackout DOE SMG can shoot supersonic .300 Blackout, which gives you rifle performance in a tiny package. You can toss on a can and swap to subsonics and get a gun that suppresses as well as a 9mm shooting subsonics.
You’re getting more range, more power, and a better all-around firearm.
The Big Changes
The biggest change is moving from 9mm to .300 Blackout, but there is more to it than that. The old Colt SMG-pattern guns are all straight blowback weapons. The .300 Blackout variant of the DOE SMG is gas-operated with a standard direct impingement gas system.
It’s also predictably using a traditional AR lower with standard AR magazines. Using standard AR mags in a DOE SMG looks like a reverse stretch design, and it’s got its own charm.
This might be one of the few, if not only, carry handle, retro-style .300 Blackout rifles I know of on the production side.
H&R is one of my favorite current brands. The stuff they’re making is fascinating and interesting. I can’t wait to see what comes next. It’s interesting to see they are diving into alternate designs that aren’t historically accurate, but still retro-cool.
