been shooting BP pistols bunches of years,have read and still read all I can,one thing I have never had a good grip on is BP measurement.I know it's by volume.how does one relate volume to say 25gr of FFFG? to me 25grs. is a weight,something I can check and see.if I'm told to pile up 25grs. of BP by volume ,I have no idea where to start.if told to pile up 25grs.by weight,I can do that.I'm pretty sure X amount of BP by volume is equal to X amount by weight.just don't know where that is. jwr