"Disco Vegas" huh...
Some folks just don't get it. They can't help it, it takes years of research to "get it".
The plain rifle thing is a myth sown by folks who haven't the skills or money to pull off a Colonial Longrifle. At minimum a rifle of the era should have; forestock moulding, beaver tailed lock panels, cheek piece moulding, comb wrist carving, buttstock carving, breach/tang carving and lower forestock carving that tastefully terminates the upper forestock moulding.
It need not be elaborate but it needs to be there and be well executed. These features in my opinion are more important than a patch box.
Even though few if any non boxed rifles are known, its still an option that the customer may not have wanted "in my opinion".
The carving on the other hand was a feature that was expected and part of the craft. Take a look a Mike Brooks' stuff at
fowlingguns.com. His carving is simple but well executed. It looks like the era work to me.
So for a 1770s era rifle well executed carving is a must have feature.
With all that said a rifle kit is a blank canvas. Even though it's a Haines kit of a 1770ish rifle, does not mean you have to build it as such.
I really like the 1800-1820 era. In this " Federal Period" you begin to see not only elaborate pieces but also plainer utilitarian rifles. You also see re-stocks of earlier pieces. A re-stock or a plain rifle of this era may not have all the carving expected on a Colonial era piece. If you go 1800 re-stock you can justify the 1770 lock, no patch box and little to no carving.
With a lock change to a English or later styled American lock, the Haines kit could pass as a 1800 piece, but not built by Haines. You could even trim it in iron and use a Late Ketland drill a tallow hole and call it a early southern rifle.
"I don't know if you can get the Haines kit in iron and no lock inlet from Chambers"
Like Keith says, a plain rifle can be striking but it is all for naught if the foundation is poor whether it be plain or carved.