Just curious how far one is allowed to deviate from "spirit of original" in the quarter bore catagory?  What I have is an original Borchardt action smithed by Charley Durham of Denver, Co. with a 26" med. heavy round brl. and stocked by Jerry fisher around 1964..Rifle is in classic style with ebony forend tip & pistol grip cap, checkered steel Neidner style buttplate...could probably pass for an 1880 era fancy stocked Sharps sporting rifle..except for circa 1960 era fixed Leupold 7X and the caliber... .25 Ackley Improved Krag.  Now Dr, Mann was playing with the .25 Krag around 1904, which fits in our self-imposed time era..the only thing different is the 40* shoulder & nearly non tapered case body.  If I were to shoot plain-base bullets, would there be a problem?  I spent the last 10 days with tight patches & JB & letting soak overnight with copper remover until patches finally came out unstained...I just had to find out how accurate it was with jacketed for my accuracy bench mark with cast.  Now the real fun can begin.

don't think that is true, I believe it is the rifle and cartridge. I have a 25 hornet ballard I believe doesn't qualify. JMO

What about the caliber.  Only traditional calibers are listed in Joe's post.