Base pin spring and screw

[Catdad]

Last night while practicing at my favorite range, I lost the the base pin spring and screw on my 1875  While I was ordering the replacement parts, I got to thinking (it's always dangerous when I start thinking; ask my wife), I don't recall seeing such things on original 1875s.  If they don't have such things, how do they keep the base pin in place??? 

[Tuolumne Lawman]

There was a catch at the end of the underbarrel web that retained the base pin.  The spring loaded Colt type screw is aaan Uberti invention on the 1875.