There are a number of loads that go down the tubes(in a negative way) when it gets cold ,PMC comes to mind right off. I've dropped birds at 30-35 yards like a rock on Friday those when it was in the 50s and had them outright fail on Saturday morning at 25 degrees on 20 yd rising gads. Yes I too saw the bird shaped hole in the pattern.

Have you tried shooting 1oz loads for ducks? They are generally faster . As for the fasteel I've not had any issues with it as it seems to be about the same 1 1/16 load in Fiocchi cases with Ballistic Prod.CSD118 wads that I hand loaded over 4756 at 1475fps. With Bs I dropped a lesser Canada at about 35yd straight up.

Marilin,syrup,etc why must we always assume the OP can't shoot ? That's just plain arrogant , mean and generally no help at all to anyone . Oh well it might be helpfull if we wanted to all shoot 500 straight every Saturday down at Moe's Trap&Skeet , but I'd bet you can't do it either.