What size of a load do you use, no, not that one

[bobcat]

Improved Modified is not the same as Improved Cylinder, it is right between Modified and Full. It very well could have been too tight for steel shot and threw ragged patterns. No way to know without actually going out and patterning the gun with the different chokes on paper. I have patterned my shotguns and the Improved Cylinder choke tube usually provides close to full choke patterns with steel shot.

[Curly]

It looks like a lot of you are shooting 12 gage chambered in 3" & 3 1/2". What is good for those (like ME) who shoot 2 3/4"? My wife is shooting a 20 Gage in 2 3/4 or 3"? I've been shooting #2 & 3 shot and my wife #4 (all we can find in 20 gage).

When I used to hunt ducks a lot (20 yrs ago).......I used 2 3/4" shells and usually I'd mostly use #2's but a lot of times I'd use #1's when I couldn't get the ducks to come right in.  And a lot of times I'd put the 1's in for the 3rd shot.  1's work great for mallards.

I used #3's occasionally and they were fine, especially for teal and widgeon and close mallards.  I never used #4's.......but back then we didn't have the extra high velocity ammo that is available today.  You can get away with a little smaller size shot if you get the super high velocity steel......like 1500 fps.

[M_59]

Gobble, To the best of my knowledge the only chokes available for the M59 were the full, modified, and Improved Cylinder. I am quite sure that is the one you have in and would be the only one I would use with steel and then nothing larger than #2's. 

[Gobble Gobble]

Thanks all. I have patterned the two chokes for Turkey using differant shot sizes but not for waterfowl (just never thought about it). I should go out and do it. I hunt Turkey now with my bow.

[h2ofowlr]

I try to duck hunt several times a week.  I have pretty much stuck to shooting Kent Fast Steel, 3" BB's.  It's a good all around shot, so you don't have to change loads if geese come in etc.  If your an accurate shooting in the 40 yard rang and not a sky buster BB's make a large enough hole the criple loss is minimal.  I used to shoot 3", 2's when the bird were consistenly under 20 yards.  Nice full pattern with a modified choke.  Minimal cripples. 
A good thing to do is grab a few different loads and chokes and see which ones pattern the best with the least amount of holes in your pattern.  Then stick with that load all season if possible.  You will become a consistent shooter as you get used to shooting a specific load and shot size.  Varying shell speeds won't be a handicap.