Skymaster F5 wing bolt question
 

Hey guys,
Pulled down my F5 yesterday wanting to get it done and nowhere can I find the 8 wing bolts that hold the blade spars tight into the fuselage. I tried multiple different sizes in there and could not find one that fit snug. Before I assume that the threads are just sloppy can somebody please tell me what size the bolts are? I'm sure it's not only the F5 that uses them so any skymaster wing bolt size may be the correct one.

To be clear, I'm not looking for the bolts that attach the female section to the formers in the fuse, I'm looking for the bolt size that goes in the bottom of the receiver and tightens the blade spar on the wing panel in.
Thanks in advance

Jeremy