Providence Tool Co. key

Can anyone tell me who makes or made this type of key for Providence Tool Co. Cuffs and leg irons?
There is an M stamped on the end of the key, but it is not M for McColl - the master locksmith and key maker.
Really it is just a rod with the correct thread type, so you have to pull on the rod to open the cuff.
I have seen a few of these over the years on eBay but never known much about them.
Paul

is there a Way to Identify the Time Period. from the Stamp ? this might give you a Clue. as to how old they are.

Can anyone tell me who makes or made this type of key for Providence Tool Co. Cuffs and leg irons?
There is an M stamped on the end of the key, but it is not M for McColl - the master locksmith and key maker.
Really it is just a rod with the correct thread type, so you have to pull on the rod to open the cuff.
I have seen a few of these over the years on eBay but never known much about them.
Paul

Click to expand...

Well the cuffs were made between 1847 and 1885 but the key is probably a modern replacement. The M stamp looks fairly modern to me, So I was hoping that there may still be someone out there who can make them.
Paul