Now, I'm really interested. I've patterned a lot of shot loads but never buckshot.
Those patterns are amazingly tight. I've read the "inch per foot" spread from a Cyl choke before. The NRA Firearms Fact book says one inch a yard for a full choke and 1 3/4" per for a IC choke.
Your patterns are way tighter than that. Maybe next weekend I take out the Ithaca.
BTW - I'm still trying to wrap my head around the other idea of deer killing patterns of buckshot at "upwards of 100 yards". Even at 1/2" per yard (which is about what the pictures were at 20 yards) , that'd be a 50 inch wide pattern with 9 shot in it.
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