Greener Martini stock bolt

[mdevlin53]

I recently purchased a Greener Martini from another member here and wanted to take the butstock off but to my surprise way down at the bottom of the hole in the stock is a bolt head. Most drawing show a slotted head bolt. but not this one. now there is not much clearance around the bolt so i will probably have to turn down a socket to loosen it the question is which one. I cant get anything dowto the bottom to measure it and i am stumped.
i did ask the previous owner and that fact has been long forgotten so any help would be appriciated.
Michael

[BCRider]

Try cutting a slip of wood 1/8 thick by the width that allows it to just fit down the hole. In the end cut a V notch. When you push the stick down the hole work it to find the spot where it bridges two flats with the shortest distance. At that point push firmly to indent the side of the V with the edges of the hex head flat. Now you can measure the distance across the two flats and go socket shopping.

If it was mine when it's out I'd take a moment to make a nice flat screwdriver slot across the head. Or drill a second recess by the bolt access hole and put the custom ground socket in there with a little padding to be held in place by the butt plate. And make no mistake about it, you'll need to grind the socket down unless it's a real cheezy import.

[mdevlin53]

As it turns out it is 16mm. the snapon socket did not fit in the hole but some yardsale single I had knocking around was just the ticket. Problem solved.