The Europeans were way ahead of the US in small arms and ammunition development. Witness the 7.65x53, 6.5x55, 7x57, 8mm Lebel, etc. The US Army was still shooting 45-70 single shots when the Europeans were selling smokeless powder, jacketed bullets, repeating rifles, etc. world-wide.
On the sporting front, the US had many more hunting opportunities and hunters than did Europe , so unless a manufacturer sold and got a real foothold over here, his market was limited, except for international military sales.
