Reloading for the .204

[Rocky Raab]

Scooter, while I might make an educated guess to start loading an unknow cartridge with a new powder (and have), I certainly wouldn't make such a guess with somebody else's gun - or face - in the balance.

See if Alliant or IMR have new loading data on their websites, ditto the bullet makers.

The next best source are published articles by known writers, but take these with some degree of caution as typoes are always possible.

One source to be avoided completely is the internet - unless the advice you see tallies with the two above. But there are too many dangerous loads published on the web - accidentally or deliberately - to believe any of them.