The Killer

Beretta 92FS

Or its copy, the Taurus PT-92. (Nope: it looks to be a Beretta, plus Chow Yun Fat doesn't like Taurus guns. He always tries to use Berettas).

The ones in this picture are Berettas, but actually, The Killer features more Tauruses than Berettas. One of the armorers from the movie used to post on a message board I visited, and he says they only had access to one 92F for most of the shoot, so they used Tauruses in many scenes.

Heckler & Koch MP5K

Ah Jong (Chow Yun-Fat) fires his MP5K.

(Fake) SVD Dragunov

The rifle used by Ah Jong (Chow Yun Fat) to carry out his assassination plot is a Chinese Type 56 (AKM) modified to look like an SVD Dragunov.

A real SVD Dragunov sniper rifle for comparison. Note the scope and mount, receiver dust cover, receiver side, magazine type, gas tube, rear stock. All are different than the rifle that Chow Yun Fat uses. He is using a fake SVD mocked up from a Chinese AK.

Norinco Type 56 mocked up to look like a SVD

AK-47

An AK rifle, possibly a Chinese Type 56-1 with a folding stock, is used in the church shootout.