Rear hub bolts size

[CFreitas]

I need to replace the rear hub bolts of my Ford and acquired bolts A-1118 for my suite cast iron drums.
Now I have a problem, the hub bolts don't hold on to the drum, they have a tangentially smaller diameter.
I attach a photo, where you can see that the originals (right side) have a square fitting (also in the drum) and the new one (on the left) has a rounded triangle!
I will be grateful if someone can help me.