Will check the holes per your advice.

I assume I can buy just the screws for the bases too somewhere?

Quote Originally Posted by SomeOtherGuy View Post
Those screws look really, really weird. Only time I've seen that is when I forcefully screwed a screw into a hole that wasn't fully threaded. I would make sure the receiver holes are fully drilled and fully threaded, and don't have metal shavings or something blocking the threads, before putting new screws in. Best way to do this is with a tap of the correct size. Those aren't too expensive to buy, but depending on your skills and preferences you may want to take this to a gunsmith.