Having shot countless short-barreled weapons, I’ve gotten used to seeing 10-inch and even 8-inch barrels. But the barrel on the DPMS is a 7-inch A3 barrel assembly. I attached the PDW upper to a DPMS lower equipped with a standard M4 stock and a Magpul MOE grip. I was surprised when my scale flashed a weight of 6.1 pounds. (Just a few ounces short of my longer ARs.) After further inspection, I came to the realization that underneath that handguard is one fat bull barrel. This barrel assembly helps the RFA3-PDW to keep the pressures at bay.
A PDW needs to deliver rounds reliably and reasonably accurately at shorter distances. It’s not a precision gun. It will be drawn quickly, quite possibly in very tight confines, during rapid, purposeful engagements to remove persons from hostile areas in as little time as possible. Working against that reliability are the tremendous pressures generated in an especially shortened AR platform.
The massive 7-inch, chrome-lined, 4150 chrome-moly heavy barrel is chambered in 5.56mm and is coupled with a pistol-length gas system. It sports a 1-in-9-inch twist, so theoretically lighter bullets, say 55 to 69 grains, should perform better out of it. The barrel is wrapped in a 6.25-inch, free-floated forend with a Picattiny rail along the top, and though the handguard is vented, it isn’t to the extent that you’d think. Under lower rates of fire, this won’t be an issue. As the rate increases, just keep in mind that this thing will be extremely hot. Included are M4 feed ramps, a must for serious feeding reliability, and an M16 bolt carrier assembly, which you’ll find in uppers built for military and police. Attached to the muzzle is a Blackout non-mount flash suppressor.