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Nowatny, was a very repected, CZ gun maker as previously mentioned. I do not know all the details but it is believed that Nowatny sub contracted WR to make the gun. The owner who used it in the video (the gun has been resold) is a most knowledgeable collector and also owns a Super Magnum Explora. He said to me when he picked it up he knew it was English...

I know the owner did other "tuning" to the gun after getting it back from Sherman. The 10 pounds makes sense to me as the Super Magnum is very difficult to shoot at 8 lbs., as the recoil is so fierce.

I know Ross shoots a "Duplex" load in his Super Magnum to get the proper velocity without exceeding pressure. Holland used a duplex load as well in their 40 grain guns. It was cordite and, not sure here, but I believe "gun cotton" or even a charge of black powder. There is also another proprietary powder that Tom Armbrust uses to get the proper velocity.

IMHO, there is no guns more difficult to load for than the Fosberry bore rifles.