Gus suggests that you and he have a volumetric measure that is graduated in single grain increments. I've never seen such a measure. If that's the case, then follow his advice.
However, if the distance between the bottom of the measure and the line marked with 10 is the same as the distance between the 10 line and the 2 line, and then the distance between the 2 line and the 3 line is also the same, etc. etc., then your measure is marked in 10 grain increments, which is more like what I'm used to.
As for measuring 23 or 25 grains with such a measure (10 grain increments), simply estimate one third or one half the distance between the 2 and 3 lines and set the measure there. One grain precision is neither necessary nor desirable, so estimating that amount is perfectly reasonable.
Yes, you can charge the chamber with the cylinder in the gun. Put the hammer in half cock, rotate the cylinder until the empty chamber is next to the barrel assembly, where the indentation is, set the ball into the chamber mouth and press it into place with finger pressure. It will be slightly less than half way into the chamber (the middle of the ball will be just a bit outside the chamber). Rotate the cylinder so that the ball is under the ram on the loading lever and lower the lever. As you lower it you should move the cylinder so that the ram is centered over the ball; the indentation in the ram will help you feel it when it's centered. Once you have it centered, use the lever to force the ball into the chamber; a moderate amount of force will be necessary. The ball should lose a thin ring of lead as it is press fit into the chamber. Force it down with firm, steady pressure until it stops, which is when it is seated on the powder charge. Give the lever a slight extra push to compress the powder and ensure the ball is seated.
mykeal, that is exactly the kind I have. Thanks for clearing that up for me.