Maybe I'm missing something here, but couldn't your friend just count the holes for rivets?

Sorry..... It's in storage AND 500 miles away at his parents. (and no, i don't have one available to count either.)

Hey Moonpup!

MSA sells the rivets and you don't have to buy them off eBay! Hurray! They usually come in packs of ten and we just counted 46. Buy 50 of them.

Excellent! That's almost double Victor's WAG. I was actually trying to count from memory and thought Victor was pretty close. Now we know.

Thanks for your help 26th-Z, and I'll tell my friend about MSA.