Parker Musket?

[OH Osthaus]

yes - 1828 is in the early timeline for a cap lock in the US - 1825 or so is about right for the beginning of general use (invented C 1820) although some builders and some buyers still liked the rocklock for years to come. on the frontier - you can find flint on the ground - not little copper caps. Hudson Bay continued to sell flintlocks through the 1800's and I believe into the very early 1900's

The conversion of flintlocks centers in the early 1830's, as the flinters became seen as out of date So its certainly possible that an 1828 gun could be either.

but if the original poster ever comes back - pictures will go a long way on deciding what this musket/rifle (its called both in the original post) is. Heck, it could be a Parker/Snow someone had his birth year engraved with - who knows until we see it