The MP661K is best known for being one of the few (if only) select-fire BB guns and can fire single, three-round, and six-round bursts - although in some markets, such as the United Kingdom, only semi-auto is available.

It is popular with both casual target shooters and airgun enthusiasts; it is excellent out of the box plus offers customization options and upgrades.

Such modifications include aftermarket/third-party and user-community alterations and upgrades such as "mod boards" that can increase the rate of fire up to 2000 rounds per minute and provide true fully automatic operation, adapters to use external propellant sources (such as 20 oz paintball CO2 tanks or HPA scuba tanks), dye kits to change the color (commonly RIT fabric dye is used), and longer barrels (higher velocity).

Some have criticized the new Backbird for having an overall cheaper "plastic" appearance, but the large magazine capacity makes it completely different kind of gun than the original Drozd.

Full auto (600/900/1200rpm) modification chips especially designed for the Blackbird are now readily available, and despite the stated 400-round capacity, in actuality, the magazine easily hold many more BBs than that.