eightbore
I really liked the RST papers in 3 1/2 and 1 1/4 strictly because they recoil a lot less, pattern much better and they do go over the 1300 fps like their 3 3/4 extra speed, that we measured properly with several shells in 7 1/2 shot size. The pattern of 3 1/2 was much better than the 3 3/4 I bought several cases and still have one case and have not bought recently, and I didn't know that they have changed their powder. But the lead high antimony (5 - 6%) shells where easy to shoot, and the pattern was excellent. In Europe you can purchase so many different brands, packed in 1o shell boxes, that is a pleasure, buy sadly many of them are not imported in the US, like Maonchi (Italian).
I did try the Italian Clever's Mirage electrocibele 3 3/4 pigeon loads, 1360 fps in plastic, and found them excellent, but they do kick more than the RST papers, in 3 1/2. I shot the same RST's in 3 3/4 dram plastic and found the recoil quite intolerable. B & P makes a good less recoil 3 3/4 pigeon shell, but it is nickel plated, and only appropriate for field or hand thrown, as they go right through the bird, remember you must used lead shot for the first barrel, I learnt that the hard way, after thinking it was bushu.
In the US the Remington STS pigeon loads 3 1/4 and 1 /4 are sweet for the first shot, and will kill tough pigeons with winter feathers, and you can use Federals or others for the second shot in 3 3/4.
Many shooters like the AA 3 1/4 which has a lesser recoil perception ( in my experience cause I have a soft shoulder) which in the summer is another option, but I will not use for faster zurritos birds in Spain, Portugal or Mexico. In Mexico I shot the 4 dram Aguila which the Mexican shooters swear by, you need a rubber teeth guard for recoil, and I though that the pattern had many holes, or the Mexicans forgot to put pellets in some shells. lol. The yellow Armusa (Spanish) brand is a very consistent shell with lower recoil.
The best shells where the made in Texas Estate before they where bought out, and have some friends that bought hundreds of cases before they where sold, but now forget about what they produce now. The last US world Cup winner Randy Ramsay swears by the 4 dram loads, at 1400 fps but he is a big guy and can handle the recoil.