Ok, so I was resizing some 243 brass tonight and happened to look at some win and fed factory ammo I had left and found something curious.
Box on left is win super x 80 gr soft point oal=2.658
Box on right is fed 100 gr soft point oal=2.570
Got curious about the difference so I pulled the bullets and measured how far they were seated into the case. Win bullet was seated aprox .240 and fed bullet was seated aprox .500. Figured may as well weigh the powder since it's junk anyway. Federal cartridge contained 39.0 gr of a short cut cylindrical powder and with an advertised velocity of 2960 fps seemed normal. Winchester cartridge on the other hand held 51.2 gr of a ball powder. Filled clear up to and just into the neck. Now I see why the bullet was only seated in. 240, as to not compact the powder. But, nowhere can I find any load data published to put 51 gr of any powder in a 243. Now I know they're shootable, only got a couple left, was just wondering what powder would they be using to have to stuff that much in there?