45C: 25 1/2 grains by volume is a moderate charge. Especially with 2F. Though you'll find that the equivalent charge in 3F runs a bit cleaner. Plus, delivers more velocity and performance. Most .44 C & B guns seem to deliver a good balance of accuracy and performance between about 25 and 30 grains. Your pistol likely being no different. Your gun will soon tell you what it likes.
Nothing wrong with using a .357 mag case from here on out, for a measure. Either solder or epoxy a bit of wire on it for a handle and scoop away.
I use discarded cases all the time, for powder measures. They work just fine.
Once you've determined your desired charge by volume, verify the charge on a scale. Dump that into your donor case, and note the powder level. Then, simply trim the case to the powder level(May have to repeat the trim and measure sequence a few times). Once satisfied that the charge is reasonably accurate. Attach a handle to it. Then, use it thereafter as a volumetric measure. It's that easy. Though often convenient, it doesn't have to be a pistol case, either. Any discarded rifle case works just as well.
It appears that you're checking charges on a scale, for consistency. That's always a good practice.
Al