The Crossfire MkI is a combination rifle and shotgun, with the two barrels sharing a single pump action mechanism. The shotgun is a 12ga bore, with a 4-round tubular magazine located on top of the buttstock. The rifle is a 5.56mm NATO barrel feeding from a bottom-mounted AR-15 pattern magazine. The initial design was debuted at SHOT Show in 1988, as a semiauto .308/12ga combination gun with a more conventional appearance, but it wasn't until about 10 years later that the first guns actually hit the market, and they were 5.56mm and pump action only.
The Crossfire was, I believe, intended for folks who expected the combination of a rifle and shotgun to produce a universally handy weapon, suitable for any circumstance. The pump action simplified the design significantly, and also allowed the designers to use standard AR type magazines during the era of the US Assault Weapons Ban (1994-2004). In reality, however, the Crossfire is exceedingly awkward and requires a non-trivial amount of practice to run reliably (that pump handle is very far forward...). The gun had an initial MSRP os just under $2000; an insane price tag that helped solidify it position as a dismal commercial failure.