Rocky Mountain is the only place I am aware of that has .410 brass longer than 3". I tend to buy all the brass I intend to use from RCC because it seems to me to be the best out there, and they make it for some really odd gauges. Oddly, they don't make it in 3".
The reason I mentioned MagTech is that it is far and away the cheapest of all the brass hulls, and in .410 it has just as robust head as the other makers, so I would have no qualms about using it in a shotgun. For that reason I would recommend trying the Magtech to experiment with wads etc.
Of course the simple thing would be to take a few 9.3x74R shells, anneal the front half of the cartridge, prime them and charge with a normal 410 load topped with a case full of cream of wheat and shoot them.
The slightly smaller cartridge rim shouldn't be a problem; the potential one is that the rim is a little thinner too, and if the chamber is too deep or the firing pin worn there could be weak ignition or misfires. Simply prime a cartridge case and fire it off empty. If there is no problem with a few of these firing and extracting, then anneal, fireform and have fun. I have never measured a 3" 410 case so don't know if they are actually 3" or not, but the .06" difference with the brass should be made up by the internal volume. You can gain something by using a glued in overshot wad, but that can be done with a 3" 410 too. Several people have the 9.3 cartridges in stock right now for a little over $1/round.
Last edited by AGS; 02/13/23 02:26 PM.
