Howdy - I have a No. 161 Marbles adapter, the hole in the side is just to pull the extended firing pin out since it has a little spring device on the side of it to hold it snug in the cartridge. Good luck finding that little bugger if it falls out in the grass! Mine still has the little 22 steel plug in it that you use to keep it stored with so the end doesn't get smooshed. I was thinking of making one out of a used brass cartridge and then machining a new extended firing pin. Do any of you know of any reason why that would be a problem? Just concerned about pressure, I certainly don't care about ruining the brass cartridge but I don't want to damage my 99.
