When the US Army decided to go with a more modern smokeless powder cartridge and rifle, they first looked at what was happening in Europe. In 1890, the U. S. Military attache in Paris obtained various samples of European cartridges for study, including the Swiss Rubin (7.5 Swiss), and sent them to Frankford Arsenal (which was at the time making no ammunition similar to what was desired) for evaluation. Frankford was very taken by the Swiss design using a .309" jacketed bullet, and decided to use it as a model. Cartridge development began in mid-1900 using European smokeless powder, as nothing suitable for rifle use was being made in the US at that time. The first production lot of late 1900 revealed that the case neck and shoulder were too thin, causing crumpling during loading. To overcome that problem, the brass was thickened in those areas, and in order to keep external dimensions the same, the bullet diameter was decreased to .306" The first bullets had copper jackets, round noses, and a weight of 240 grains. Many other evolutionary changes to the .30-40 cartridge were made over a period of several years, including increasing the bullet diameter to .308" and decreasing the weight to 220 grains. In late 1895, one significant change involved increasing the thickness of the case drawing blank to make a stronger solid base (it had been a semi-balloon head up to that time), to address case rupture events experienced in the field. That is the reason that the post-1895 cases are heavier than the early ones.