was told it was built on a monoblock not sleeved barrels
With respect to double rifles, those words usually mean a conversion. It's possible that it's a purpose built new rifle with mono-bloc barrels, but I doubt it. I'll just say that I don't know of anyone building a new rifle with mono-bloc barrels in that caliber. I'd be asking what kind of action it was built on. I seem to recall that Cabelas has had a .450 No. 2 for sale that was built on a Merkel 12 gauge action with sleeved barrels. Who built this one? What price? Mono-bloc and sleeved are essentially the same thing. There is a difference, but I don't view it as significant in this application.
Bertram is notorious. I've used it, or rather attempted to, in several DR calibers. Personally, I avoid DR calibers that would force me to rely on it. For .450 No. 2, I'd probably get in contact with Huntington's and see about getting an order brought in from Dieter Horneber in Germany. Horneber will make anything if he can get a large enough order, and it's good brass.
btw it's a .450n.e. not a bp.
That should be true by definition. The .450 No. 2 was designed specifically for Cordite, and was never loaded with black.
