Pheasants are a bit more tenacious than doves, or, grouse, or woodcock, or quail.
I remember recoil at the patterning board. I don’t when shooting in cold blood at birds.
I have had 20 gauge guns (more than one, actually) that threw lousy patterns with 7/8ths ounce loads. To a one, they straightened right up with 1 ounce loads. I own a Richland double that weighs more than a few 12s ‘aboot the place, that throws superb patterns with 7/8th ounce loads. Heavy little pig, too, over 6 1/2lbs. But, it has 3” chambers. To be expected, I guess.
I don’t know that I have ever loaded a cartridge that was going 1450fps. That sounds harsh.
Best,
Ted