David & Will: The encapsulated mainspring used circa 1899-1906 is the type lock style - except for the 2 pins which started in 1907.
The tang is the 12 ga. 1899 style.
David, thanks very much for sticking with me thru this!! I'm now convinced this gun was mfg. somwwhere around 1900 and maybe of carry over parts. Again - thanks. Jim Thomas