Very cool guys. Thanks!
Unfirtunately, I had a problem with the very first round I chambered. Had to take the thing apart to get the cartridge out of the extractor.
Won't be able to try the reloads for a few weeks until Marlin is done working on it.
As far as I can tell, it a problem with one of the following things: the extractor claw, the ejector pin, or the bolt face. The cartridge actually loads into the chamber fine but will not eject. Lever comes back to the point that most of the cartridge is free of the chamber, but then hits a hard metallic 'clunk' the last 1/8th".
Anyhoo, I loaded the 350 grainers ( Hornady Interlocks) with 52 grains of H4198 and I have some barnes 300 grain XBullets that I will load with 55 grains.
Wish me luck!