take a bead on (someone or something)
1. To aim at someone or something with the sights on a firearm. I managed to take a bead on the enemy sniper but had to wait until I received the order to fire.
2. By extension, to focus one's attention on someone or something so as to deal with or attack him, her, or it. The candidate took a bead on his opponent's poor political record during the debate. The president has pledged to take a bead on the growing problem of adolescent obesity.
3. To thoroughly understand, appreciate, or comprehend someone or something. The team just has to take a bead on the severity of the cyber attack before we can implement any meaningful fixes. I couldn't understand him at first, but I'm finally starting to take a bead on my sister's boyfriend.