I'm sure 54ball can add to this but, this is a picture of the "Transitional Rifle" I built from a "kit" from Pecatonica River Long Rifle Supply.
According to Pecatonica the intent of this gun is to simulate the style of rifle that would have been made by Germanic gunsmiths who were familiar with Jaeger rifles in the early to mid 1750's.
It is similar to a Jaeger, with a shorter, thicker stock, more drop at the wrist and a shorter swamped barrel than would find with the later style "Kentucky" rifles.
The trigger guard rail stands well off of the stock and the lock style is early Germanic.
The barrel is a swamped, 37" long in .54 caliber.
The "Christians Spring rifle" is an example of this type of rifle although there is much debate as to whether it was made in the 1750's or later.
In either case, a shorter, stockier rifle does exist and this rifle is somewhat similar to it.
Perhaps the biggest departure my rifle has from a rifle made in the 1750's is its brass patchbox.
Most rifles made in that era used a sliding wooden patch box cover.
When I built it (years ago) I thought a very simple, early metal patch box might serve to make it a "little different".