history

Hello all. I was wondering if someone could help me with a musket question. What is the history behind brass lock plates. Where and when were they used? Who used them? What time periods are they appropriate for? Or any other random info you have about them would be hugely appreciated. Thank you.

For sale & a very RARE find! King William IV saddle carbine lock. Has a slide safety and an "internal" frizzen spring. The lock plate measures 5.5 inches overall and is marked with a crown, W.R., TOWER and dated 1835. Fully functional with patina intact and correct internal maker markings...