I thought I would spring for the good stuff to feed my new 870 supermag waterfowl camo so I picked up a box of Federal Premium 18 ball 00 buckshot with flight control wad.
The shotgun has a 26" barrel with a "waterfowl" choke which seems to be roughly halfway between my other two shotguns with full choke and improved cyclinder
Anyway my target is 3'x3' and at 40 yards I'm ony getting 11 or 12 balls on target, but in a very tall, narrow oval . . . any ideas why I would be getting a pattern like this rather than the usual circle of shot?
Chokes for waterfowl have traditionally been very tight ("extra full"). Chokes constrict the shot column. However, shot (as opposed to buckshot), is hardened by the addition of arsenic, and hardens when it is rapidly cooled ("chilled"). The hardened shot restricts deformation induced by the constriction of chokes. But, buckshot is not made in a shot tower or has it elements added to harden it because it is "swagged" (formed with pressure in dies when it is cold), and is made of pure soft, lead. Therefore, generally, it is deformed by the use of a choke. Usually, the more open the choke, the better the pattern will be because there is less tendency for the buckshot to deform (flat areas on the buckshot), and curve out of the pattern. Put your most open choke in your gun and test it to see if your pattern is better.