Hood Bolt Size/Thread

Yeah, I picked up some 5/16 bolts but they dont seem to wanna go past the first 2 or 3 threads on the hood. But, they thread all the way into the fender J nuts. I'm not really wanting to just torque down the bolts into the hood and do some damage.
Has the hood been off the car long? You might want to chase the threads in the mount holes with a starting tap of the bolt size. They could have some crud in the threads