draw a bead on (someone), to

draw a bead on someone or something

 and get a bead on someone or something 
1. . Lit. to locate someone or something in the sights of a gun. Fred drew a bead on the target and pulled the trigger. The hunter drew a bead on the deer.
2. Fig. to prepare to deal with or obtain someone or something. As soon as I get a bead on how widespread the problem really is, I will set up a meeting about it.
See also: bead, draw, on

draw a bead on

Take careful aim, as in The debater drew a bead on his opponent. This term, dating from about 1830, alludes to the bead on a revolver or rifle, that is, a small knob in the foresight. [c. 1930]
See also: bead, draw, on

draw (or get) a bead on

take aim at with a gun. chiefly North American
1994 Ontario Out of Doors Few moose will pose majestically right at the water's edge while you draw a bead on them.
See also: bead, draw, on

draw a bead on (someone), to

To take careful verbal aim at a person. An Americanism dating from about 1830, the term comes from aiming a revolver or rifle, on which the “bead” was a small knob on the foresight. It was being used figuratively by about 1930.
See also: bead, draw, on