FrankenMauser, you are right, but... some guys enjoy fabricating ammo just about as much as they do shooting it. Where I live we don't shoot much in the winter, but I'll load up 500 of these brass 410's to shoot this summer.
Where I live Magtech brass costs $2.40 (Canadian) each, plus shipping. That equals $1200.00 for 500. I could buy another shotgun for that. As for 303 Brit. cases, I have already accumulated 750 from the range that didn't cost me a cent. When I lock the carriage and use the cross feed on my lathe it takes 15 seconds per case to turn the 303 rim to the proper thickness. After fireforming I use a special expander plug to increase the bottom half of the case to the proper dia. The result is SAAMI 410 specs except for the solid web base, which does not matter. (Except for the web, there is no extra ten-thou clearance for the full body of the case.) This case is strong, and thicker closer to the head than the Magtech.
Because of my home made polyethylene (HDPE) shot capsules, case capacity is more than adequate even for the largest recommended loads of shot. These modified 303 cases easily accept large pistol primers just the same as Magtech brass does. My cardboard overpower wads work just fine and cost nothing. I am happy with the 1150 ft/sec I get, plus excellent patterns that consistently nail clay pigeons at 35 yards. After 150 firings, there is zero lead fouling because the shot does not touch the bore.
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Ecc 11:4 He that observeth the wind shall not sow; and he that regardeth the clouds shall not reap.