Rio MG Slugs Deal Damage

Shotguns are cool. Slugs are cool too. RIO Ammunition decided that regular old slugs were not cool enough—so they gave us their line of Royal MG slugs that deal massive damage. Rio classifies their Armored MG style slugs as big game rounds. I can’t imagine too many large animals that could stand up to a well-placed shot with one of these heavy projectiles. The load weighs 1.125 ounces and travels at an astonishing 1,540 feet per second. That equates to nearly 2,625-foot pounds of kinetic energy out of that old 12-gauge shotgun. To put that in perspective, a baseball travelling at just over 500 miles per hour would hit you with roughly the same amount of energy as this slug.

Unfortunately, for your target, the RIO designed the lead portion of the slug to fragment upon impact, dumping all the energy into the target directly, creating massive trauma. Running through the middle of that lead slug is a steel rod with a pointed tip, which can poke holes in barriers or thick animal hide. When firing, we noticed that these were not exactly low-recoil shells. The massive amount of powder tightly packed in the shell helps provide substantial recoil on our lightweight tactical shotgun. To my delight, our aluminum framed Mossberg stood up to the task without any problems.

This slug bears a striking resemblance to a Brenneke style slug. If you are unfamiliar with Brenneke style slugs, here is a refresher. A German gun and ammunition designer named Wilhelm Brenneke developed the Brenneke style slug in 1898. The original Brenneke slug is a solid lead slug with fins cast onto the outside, much like a rifled Foster slug. In the case of the Rio, the steel air rod adds greater penetration, while the lead projectile fragments. Originally, there was a plastic or felt fiber wad attached to the base that remained attached after firing. This wad serves both as a gas seal and as a form of drag stabilization, much like the mass-forward design of the Foster slug. The fins, which Brenneke designed in the projectile, impart little or no spin to the slug. The actual purpose of the fins is to decrease the bearing surface of the slug to the barrel and therefore reduce friction and increase velocity.

Unlike most Brenneke type slugs, RIO designed this particular slug to fragment considerably on impact, making it extremely deadly. The sharp shoulder and flat front of the Brenneke is similar in dimensions to a wadcutter bullet. This means that its external ballistics restrict it to short-range use, as its accuracy is similar to that of an American Foster slugs while retaining the improved penetration and slug integrity of the Brenneke design.

This particular design seems to work as a multi-purpose slug round. Since the Rio MG can penetrate barriers while still causing lethal damage, this slug is equally adept to both hunting and law enforcement applications. In this role, shooting through barriers may be a necessity. Changing out shotgun rounds in the middle of a gunfight with a perpetrator could get you into serious trouble. As a law enforcement or large game hunting shell, the Rio MG slug will get the job done, no questions asked.

The Mission of Cheaper Than Dirt!'s blog, The Shooter's Log, is to provide information—not opinions—to our customers and the shooting community. We want you, our readers, to be able to make informed decisions. The information provided here does not represent the views of Cheaper Than Dirt!

Comments (5)

  1. 2″ LexGuard 3 2X4’s 5 collapsed cardboard boxes. 89% intact with steal core. Massive penetration!!!! Need I say more.

  2. I would have liked to see some pictures or specific numbers and details on barrier penetration. That and some ballistics gel testing would have been outstanding. But gratz CTD, you seem to have done the most detailed review thus far, with the most info given. I’ll see what else I can find, and hope to add to it soon with some barrier testing. Thanks CTD

  3. DAAAAM That borders on the unbelieveable. If additional “independent” testing bears those numbers out, then a handful of these along with various other 12 ga loads, there are a whole lot of Alaskans who have been waiting a long time for the RIO MG Slug. Dang, alot of folk in Elk & Moose country may be kind of impressed.

    Seriously in a backwoods cabin gun in Alaska, given available loads, what else would you need?

  4. With those figures, it would almost seem like we almost have another class/type ammo for defense/hunting scenarios. Very impressive. I mean, it’s that much heavier, that much faster than traditional factory fodder, and with a steel core, it’s like it’s in a class by itself. I currently (after theft) have only one 12ga, and it’s a single shot modified Pardner of mine, down here from New England. I am however, looking to get a Mossberg M 590 A-1, and will at some point, but just learned of the Norinco 982, and am now researching all I can find on this gun, probably comiting to one soon. Hopefully, this will be a safe, reliable platform for this powerful new round, as well as quite a variaty of loads for many years. If this new round is widely accepted by the masses, perhaps it will be readily available for as many years down the road.

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