As used here, grain is a measure of weight- ABOUT 1 gram. Smokeless gun powder is usually grey to dark grey, and may consist of tiny flakes, disks or rods.
I'm not sure what you mean by "truest" smokeless powder. If you mean "which powder will emit the least amount of smoke when you shoot" then answer isn't that easy. The amount of smoke depends on the conditions of combustion such as burning rate, chamber pressure and quantity of powder. A small quantity of fast burning powder would emit less smoke than a large amount of slow burning powder. If the goal is to find the load for a given caliber that will smoke least, in general you should look for the fastest burning powder that is recommended for loading that caliber and bullet weight.
powder
It has a big Baking Powder label on it
it would look like two and three quarters of a gallon.
Like black grains of rice, or a little smaller.
Orzo is the pasta that is shaped like rice.
Soil Consists of solid grains that have various sizes. Like coarse grained particles such as boulder, gravel and sand also fine grained particles such as silt and clay. The grains are classified according to their sizes. A size of solid particles ranging between 0.06 mm and 0.002 mm is know as silt. It's just looks like a powder.
a dry powder
A very small sandcastle.
this is what you touch a moth powder if you touch a moth powder its look like a sand the sand make you lucky sometimes.
Could be as early as 1905 (if it is, it was made for black powder rounds - do not use modern smokeless, it could blow up. have a gunsmith check it out) But a lot more info is needed. Like - what does it look like, what are the grips, does the cylinder tip out, does the top open, etc.
White Powder