THE BASIC PRINCIPLES OF IMR GUNPOWDER RELOADING DATA

I will fall back some grains and perform up and see what transpires .I've and use alot of the 2400.Bought two in the previous Enfields No 1 MKIII's and would want to test it in them also,have not loaded for them but but beeing a rifle bored out to 410ga it would be that I could bump them up a tad extra,a standard 410 shotshell wont in good shape th