the barrels on my 410(s) measure .387-.388 at the muzzle , full choked .
They are single shots and I use only brass hulls.
I have worked up loads using #9 shot in weights from 9/16- 7/8 oz weights.
All shoot well and are not in no way overpowered.
I use 2400 powder in different grains for different shot weights up to 14.5 gr.
I want to cast some RN slug loads for it and am thinking about a rifle type slug perhaps with a hollow base.
I see that the factory loadings for 410 slugs are very conservative from 1/5 oz up to less than 1/2 oz.
using a calculator or my digital weight scale a 9/16oz shot comes in at only 246 gr. 1/2oz is 219 gr.
What would a good slug load be and not be too much?