3N38 POWDER NO FURTHER A MYSTERY

I will fall again a handful of grains and work up and find out what transpires .I have and use alot in the 2400.Acquired 2 from the previous Enfields Number 1 MKIII's and would like to attempt it in them also,haven't loaded for them yet but beeing a rifle bored out to 410ga it might be which i could bump them up a little bit far more,a normal 410 s