I really like...
My grandfather was involved in field testing the Pedersen rifle in the late-1920's. Until you mentioned it, I had almost forgotten the stories about the conduct of those tests he told me when I was a child.
this cartridge. I once owned a Vickers-Pedersen SLR in this caliber (and still have a full case - 1680 rounds - of the FA29 ball ammunition. The rifle was a hoot to shoot, though the toggle would often hit the brim of one's hat, and would have given you a headache if you were wearing one of the old soup-plate helmets. It was a mechanical marvel, but would never have been so fine a military rifle as the Garand (originally developed in the same caliber) turned-out to be, IMO. The cartridge would have served admirably, though, I think, since it was ballistically similar to the cal. .30 M1 ball up to 1000 yards, though it would not have performed as well in special purpose types such as AP and tracer, etc., due to its limitation to lighter projectiles.
The rifle I currently have in this caliber is the only sporting rifle I've ever found chambered for it (though I know many more must have been built, considering the large amount of surplus ammunition sold-off in the 1930s): the rifle was built about 1943 on a 1917 action by Hammer and Gipson (Vernor Gipson, of wildcat fame) in Chicago, and is very nicely made (and accurate), though the stock is actually pieced-up from the military original.
My shooting ammunition is loaded in both the FA brass and re-formed 6.5x54mm MS.
I later acquired a Remington Model 30 rifle chambered for the .30 Remington, which is perfect for the .276 round, and intend to one day make up another rifle in .276 on that action.
mhb - Mike