5.7mm x 28mm Weapons (Existing and Proposed)

FN produces various models of the Five-seveN and of the P90.

Clymer produces chamber reamers.

A Carbine Conversion Unit (CCU), as produced by MechTech, would be interesting.

A re-chambered Beretta CX4 Storm would be interesting.

It might be easier to work with something that already shoots small .22 cartridges (like the .22 Hornet, .22 Remington Jet, .218 Bee, .219 Donaldson Wasp, etc.)

Other options might be anything that fires the .224 BOZ.

Form-factor-wise, anything that fires the .30 Carbine cartridge might also hold promise. Performance using 5.7x28 ammuntion would probably be less than .223 MIKE, 22 Spitfire (AKA 5.7mm Johnson, AKA MMJ 5.7mm), or 22 Carbine wildcats. The M1 and M1A1 carbine configurations, and Iver Johnson Enforcer pistol come to mind. The Johnson Spitfire Rifle is just one example.

Conversions from .223 might include the Olympic Arms OA-93,

Feeding 5.7x28 cartridges into an AR might be accomplished similarly to OA's pistol caliber conversions, but using modified M1 magazines instead of modified Uzi magazines.

Something like the Colt MARS (Mini Assault Rifle System) would be the goal.