The operation of the PMX is based on a blowback system designed with a closed-bolt firing mode. Barrel and bolt are machined from a special high-strength steel to withstand harsh environments and abusive conditions.
The PMX three-position fire selector is easily accessible for right and left-handed users. The Beretta PMX submachine gun is compact and can be easily concealed by folding the stock with the push of a button. An oversized button releases the magazine, guaranteeing easy operation while wearing gloves.
Special surface finishes and treatments are applied to the firing mechanisms and other areas where friction exists to reduce wear and maintenance needs. Multiple Picatinny rails allow the PMX to be easily customized by mounting around the receiver a combination of illuminators, pointers, and other enablers.