RE: How many 100 grain loads in 1 lb of powder?
As others have said, 1lb=7000 grains...BUT...
Powder canisters are filled by weight, so you're getting 7000grains of powder when you buy a pound, give or take a few grains.
However, you measure and load your rifle by volume, using a volumetric powder measure calibrated to black powder. In other words, if you set your measure to 100gr, and measured a charge of 2f real black powder, theACTUAL weight of the charge will be roughly 100 grains if you weighed it on a scale. The problem is thatblack powder substitutes areNOT of equal density asblack powder, but are designed to still be measuredby equivalent volumeof blackpowder. To put it more simply, measuring 100 grains by VOLUME of Pyrodex, for example, will not mean that you have 100gr by WEIGHT of Pyrodex, but the load will perform similarly to the same volume of black powder (black powder equivalent). If you measured 100gr by volume of Pyrodex and dumped the charge onto a scale, it will NOT weight 100grains, and might not be even close. That is why there are warnings on the labels of Pyrodex and such that say that it must be measured by volume equivalent to black powder, not by weight. 100grains of Pyrodex by weight is a lot more powder than 100grains by volume.
So to answer your question, the only way to know is to measure a 100gr charge by volume and then weigh it on a scale.Then divide 7000 by the actual weight of the charge to find the shots/lb.
Mike