Thanks Nick, I reached the same conclusion as far as no existing shell holder. Problem is rim thickness is .088. Upon miking the Bertram brass (BB), I found the inside diameter of the shellholder was OK and there was no problem with fit.
You are correct on the diameter of the brass (.630) however, interestingly, the base has a 45 degree bevel reducing the base to .588.
I like this brass as it is extra thick. Brass formed from 348 has short case life.
I did manage to find a post on another forum where someone "dremmeled" a shell holder to make it fit. Since the case is beveled, Dremmeling looks easy.
I do have two 8mm Lebel shelholders and this will be my next alternative. I will let you know how that works.