How far does a 25 caliber handgun shoot?

Effectively, and expecting to be able to hit your target, you'd be looking at about 25 metres, under ideal circumstances. The bullet may travel significantly further, but most of your 6.35mm pistols are "pocket pistol" designs, intended only for the closest of ranges. As far as how far the bullet will travel, it may travel up to 500 metres or more, under the right circumstances.