Don't be caught without an extra bolt on range day !!
1/2" x 1 1/2" Grade 8 zinc carriage bolt and self locking nut.
GRADE 8 Bolts are High Tensile Strength bolts which prevents the bolt heads from breaking off due to impact forces on the plate. Low Tensile strength hardware store bolt heads will pop off easily due to these impact forces giving the illusion they were shot off.
These grade 8's are hard to find at the local hardware outlets. They are NOT indestructible and can punch through with a center rifle hit so have a couple on hand.... just in case.
The pic below shows the bolt being hit and flying through the air.