Question.....I have new Magtech brass shells. I have .557" round balls which weigh 260 grains each. Plastic wads which I will cut the petals off of. Shotgun is an as new single shot 20 gauge 3" magnum. I am not a shotgun loader but have reloaded for years both rifle and pistol. I am trying to find a load which suits my powder choices which are L'il Gun and SR4756. I have searched here and found a load....... 500 grains over 36.0 grains of L'il Gun. Would that be safe with 520 grains over 36.0 of L'il Gun in the Magtech casings? Thanks, Dave