If you shoot a semiauto, it might make a difference in how the gun runs. In a pumpgun, it should be no big deal. But reliability in the gun is consideration number one, no matter what else is part of the equation.
Two ways to get reduced recoil - less payload, or less powder. Either equals less downrange performance to go along with the reduced recoil, the laws of physics will not be denied. Not likely enough lower oomph to make a difference at genuine across-the-room range though. If the reduction in recoil is important enough to you to sacrifice a bit of performance, then no doubt the tradeoff is worth it.
Try Fiocchi 12LE00BK, a 9 pellet 00 load with hard lead nickel plated pellets. It's the softest kicking buckshot I've found so far (
http://www.midwayusa.com/viewproduct...tnumber=482134 to see it, shop around for best price). It comes in 10-round boxes and should be pretty widely available - and you shouldn't have too much trouble dealing with the price. It patterns reasonably well, and does better in my limited experience with a touch of choke. Here's a report on some limited patterning with a couple of guns/chokes I did a few years back -
http://www.thehighroad.org/archive/i.../t-167864.html fwiw.
lpl