I'm helping a neighbor clean up his late uncles Mossberg 183T .410 shotgun. It's not in too bad a condition; just a lot of surface rust and dried oil/grease. The only missing part is the bead sight. Can anyone tell me where to get a replacement? I've done some searching on the internet today but found nothing. Does it have to be a Mossberg part or are these beads interchangable with other manufacturers? Obviously, I don't know much about these things... any help appreciated 
