The British military decided to organize their disparate small units of riflemen into a single standardized group in 1800. The 95th Regiment - the British Rifle Corps - was founded and it was equipped with a pattern of rifle designed by one Ezekiel Baker. This was a .625 caliber rifle with a 30” long barrel and a remarkably slow 1:120” rifling twist. That rifling was deliberately chosen to balance rifle accuracy with ease of loading and it worked quite well as a compromise solution. The Baker was considered effective on individual targets to 200 yards (300 with a particular skilled marksman) and area targets out to 500 yards.

The Baker was used throughout the Napoleonic Wars and only replaced in 1838 by the Brunswick rifle. This example is one of the original 1800 pattern, modified in 1815 to replace its distinctive bayonet bar (used to fit the large short sword bayonet made for the Baker) with a typical socket bayonet lug.

BritishMuzzleLoaders playlist on the Baker:
https://www.weaponsandwar.tv/baker-rifle