I've got a case of hevi bismuth #2 3" 1.25 oz loads ive been trying to pattern for duck season and looking for some help. Looking to shoot them out of an sx3 (invector plus) and browning b80 (invector). Started with both guns in an extended range carlson .710 and .700 respectively. Patterns weren't even 50% on 3×5 patterning board at 40 yards. Didn't have anything tighter until turkey chokes in other guns. Went to an 870 and Charles daly to do some testing and shot an undertaker .675 and tight wad .660. Patterns were about 60% 30" circle but uneven with a fair amount of flyers.my hunch is im overchoked at this point and need something in the .680 range but looking for any suggestions I can get. Normally, I'd just buy chokes and test until I found what I liked but I've never been a fan of anything hevishot anyway and only have a case of these and it will be my last so im just hoping to find something usable to get these shot up.

Try using a more open choke....

I should've mentioned that. I started with improved cylinder up to light modified in the sx3 in the factory and carlson waterfowl chokes. All were as bad as the extended range carlson mentioned and saw the patterns improve from that to the turkey choke which was what gave me the inclination that somewhere between the full carlson and turkey choke I where I need to be. I do have a couple straight cylinder chokes I could try but with the testing I'd tried at that point made me think I was going the wrong direction.

I don't have much to suggest.

But, I shoot a lot of 1 ounce bismuth loads in a 16 gauge and it works great. Mostly an IC choke...or Mod on my 2nd shot. I'm shooting pheasant over pointing dogs. I don't take 40 yard shots, generally.

Interesting that you had similar results in that many guns.... Bismuth tends to fracture so maybe the open choke would actually help,
,,,or, sell off that case and forget about it, lol

I'm out of ideas...

Cut’em open, dump Bismuth, reload with #4 lead, crimp’em back down, kill ducks.

Well fellas your responses thus far are about what im coming up with too. I have never been a hevi shot brand fan and picked these up cheap, hoping to have something to get me by. Have been loading tss the last couple years and just have a hard time going back to steel on some of the late season diver hunts we get in to. But with the tarrifs its really priced me out of that game. I have done quite a bit of patterning and these shells have me perplexed. I was just looking for the cylinder choke I have and did find an old patternmaster long range I use to use for geese. It uses the stud rings instead of constriction so maybe coming at it from a different angle will do the trick but, I don't have high hopes, that choke loved the old federal 3.5" t shot and has been adequate at best with anything else I ever tried it with.

Just out of curiosity what’s the velocity on those shells?