The Chambers kit is the Marshall gun- which is unsigned and attributed to Christians Spring (appropriately) and as indicated above, has been variously dated from 1740-1770. There are learned opinions on whether the gun is intact as originally built or a restock done "in period" after a catastrophic break.
I had the good fortune to handle the gun in the early 1980's and favor the idea that it is a restock. I see it as a F&I War period type of rifle- the furniture, lock, barrel profile, etc are all appropriate for 1750's-1760's. It's a beast of a gun in the hand and the differences between it and many 1770's era rifles are black and white. There's no mistaking that this is a Germanic gun in form, not an evolved American longrifle form.
I guess in summary, we early rifle "stitch counters" don't like to lump all Christians Spring rifles together as they span some stylistic variations and a couple decades when the longrifle was rapidly evolving in style. There have been excellent Marshall rifle kits made and so now there are more existing CS rifles than probably ever existed originally, and most of the new ones look exactly the same.
