I have a drilling in 7x65r and a bolt gun in its "sister" 7x64. They are about the same as a 280 Remington. They are not 1000 yd cartridges but, I don't hunt at 1000 yds. The 7x64 does well on targets at 600 yds.

All that being said, the 7x65r is a good cartridge for a singleshot or double rifle. However, it isn't a Brit cartridge and it seems like WR could have used a flanged Brit cartridge. But, that is my 2 cents (and 2 cents won't get a cup of coffee)