.410 round ball slug advice

Hi everyone,


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.


Cheers, Mike

I can't offer a Herco load but your last point above, should be your starting point.

Is the ball a tight fit, if so that will limit where you want to go with load development. Also, do you have a published recipe with these components? That would be the preferred method for starting load development. If the answer is "no" but the 11.5 gr charge was where you started with your .375 ball formula, then that is probably a reasonable place to start. A roundball of .410" and pure lead will weigh 104 grains and of 1:10 will weigh 99grs.

Have you measured choke on the new 410? Cyl choke on a 410 is rather odd, unless it's been cut. So while you say "reliably informed" I am reminded of Ronald Reagan's approach to Strategic Arms Reductions: "Trust But Verify".

I only use Alliant 410 to load for 410 so I can't offer a load on these specific components.

Thanks for the quick reply RPRNY. No I dont have any published loads so treding carefully. Thanks for the direction on the weight, i'll check them when they come in.

unfortunatly its not really possible to check the choke due to the gun construction, they come out of the factory with full over barrel 'silencer' that is fixed in place, its about 28", the actual barrel is only 15" inside but the case cant be removed, only the baffles for cleaning. These are a relatively cheap french gun, but from what i read are designed for slugs so hence the cylinder choke (subject to being told for certain by the factory - ive sent them an email and testing a ball through).

good advice though, i like my fingers and dont really want to damage the new gun...!

In my .410 cylinder bore I use .425 pure lead round balls with 10 grains of Unique and a wad column to fill a 2-1/2" shell. The same amount of Herco would be safe.

Many thanks Outpost75.