What makes 'St-n-c-tt-r' a 'smirking pun'?

This passage comes from Walter Isaacson's “Benjamin Franklin: An American Life.”:

Franklin wrote about a husband who caught his wife in bed with a man named Stonecutter, tried to cut off the interloper’s head with a knife, but only wounded him. Franklin ends with a smirking pun about castration: ... Some people admire that when the person offended had so fair and suitable opportunity, it did not enter his head to turn St-n-c-tt-r himself.

The above passage can be found in Google Book here: https://books.google.com.au/books?id=aWwUBAAAQBAJ&lpg=PA425&ots=O1Kchfi-2t&dq=St-n-c-tt-r&pg=PA425#v=onepage&q=St-n-c-tt-r&f=false

The complete listing of the original Benjamin Franklin's article: http://www.historycarper.com/1731/06/17/a-certain-st-n-c-tt-r/

I don't quite get how St-n-c-tt-r works as a pun here. How does the spelling of St-n-c-tt-r relates to the act of castration? Did Franklin use the absence of some character to mock the removal of the body part of the victim? Or is there something deeper to it?

Solution 1:

The pun appears to reside in the fact that stone is a colloquial/slang term for 'testicle'.

The essential meaning of the passage

Some people admire that when the person offended had so fair and suitable opportunity, it did not enter his head to turn St-n-c-tt-r himself

could therefore be rendered as

Some people applaud him for not deciding to cut off the testicles of the interloper when he had the chance

To spell it out, 'stonecutter' would mean 'cutter of testicles' in this context.

I assume the bowdlerizing blanks are being employed to obfuscate the vulgarity of the pun.