Fabian thanks for the great advice,
One problem is the bolts are 90 degrees to the face of the part that gets the only vision measurement and then picked. The nut runner robots come in after vision is run. The vision is run on the part, the material handler moves to pick position and grips part, and finally the nut runners come in. The bolts are removed and the part taken out.
The nut runner robots originally had vision cameras of their own but they were taken out for a few reasons, some being ehat you mentioned, FOV and trouble finding the bolt which lead to higher cycle time, the biggest reason.
Any ideas for a better search without vision?