It's not a .25 cal, it's a .30 cal (7.62 mm) bullet in a .95 (25 mm) long case, hence 7.62x25
In regards to the welding issue, the 7.62x25 has twice the power of the 32ACP, until the appearance of the 357 Magnum it was the most powerful cartridge available. The cartridge is also a bottleneck shape, so there's less material in the insert, and more hot gasses to heat it up. No idea if you can actually achieve a weld, but I can see how that could get sticky.
F 135 - the right choice
Last edited by mapsjanhere; April 24, 2011 at 09:16 AM.