There are quite a few photos of half stock pistols made by the Hawken brothers. This includes those stamped "J & S Hawken"... "S Hawken"... and even one by Jacob Hawken. All are percussion and in the style of English half stock dueling pistols that were very popular in America after 1800.
To me... and this is just my opinion... it seems there were 2 GENERAL styles of guns being made in Maryland in the 1st quarter of the 19th century... those who were following the American/Pennsylvania style... and those following English styles.
Now... a whole bunch of people are going to get there undergarments in a bind over that statement. Yes... guns made in Maryland were a whole different school... or schools (plural)... I'm not disputing that. What I'm talking about are the clearly unique American styles that were being made in America... what many call "Kentucky" rifles... evolved from the German gunmaking tradition... vs the clearly different English styles that developed at the very end of the 18th century.
Hawken full stock rifles seem closer to the American "Kentucky" style, while their half stock rifles are more closely related to the English style. So it would appear they could go back and forth with regards to long guns. With regards to pistols, they seem to have preferred the English style... as did Philip Creamer... another Maryland... and later Illinois and Missouri gunsmith. Some existing half stock Hawken pistols are actually believed to be English made and imported by the Hawken brothers.
From what I've read, true American "Kentucky" style pistols are quite rare and were only made in a few areas. Given the popularity of the English half stock style of dueling pistol at the time, I find it very doubtful, but not impossible that the Hawken brothers made full stock pistols during the time they were working in St Louis.
Just one guy's opinion.