New to the forum, but been a fan for a while. Im after some advice if possible. Ive bought a bretton and guacher phantom, its a fully moderated .410 with and im reliably informed its a full cylinder / no choke. To make the most of this and get the best accuracy ive bought some .410 round lead balls (not delivered yet). Ive had the same ball in .375 and they are superb quality, finish and size and work well in my other .410 that has a modified choke but they aren't ideal for this cylinder bore. Im not sure yet what the .410 ball will weigh in at, im guessing around the 90-95gr mark (the .375 balls come in on average at 79gr).
My plan is to use 2.5" cheddite cases (but may have to go to 3") primed with the cx50 ('coolest' 209), powder of which ive got Herco then simply a gualandi launching rod (the one sold by ballistic products and used with the .375 ball and what they refer to as the light game slug), single .410 ball and roll crimp. I would like to put an overshot card on but im worried this is a bit risky with this close fit.
Can anyone recomend a good but safe starting charge for the Herco. My feeling is to start with 11.5gr and aim to get to 13.5gr but thats just based on weight and with the closer fit between the balls and the barrel I'm a bit worried the pressure spike might be a bit severe, which id rather avoid obviously. Maybe this close fit doesn't make a difference but my gut is telling me it probably does...?
Has anyone loaded this before, Herco is my preference only because its what ive got lots of and it seems to do ok on the lighter loads, i know its a bit fast compared to lil' gun or 2400 but its not that far away.
oh, and i will test the .410 ball down the barrel first, im assuming this sorr of fit should be snug so may need a but of help but more just gentle pressur
Any help or advice would be really appreciated.