I just heard that the Federal shotgun shells I have been getting from Walmart are hard on the gas system of the Beretta 391 series shotgun.
There are few subjects about which there is more mis-information than guns and ammo.
Are there some that will shoot cleaner? Sure
Are there some that will shoot dirtier? Yes
Will you find some you like better? Probably
Will you find some you like less? Maybe
Will they hurt your gun? Highly unlikely
May you have to clean your gun more often? Possibly
If you are figuring on putting 100,000 rounds of them through the gun it MIGHT be a consideration, but even then, probably not.
I shoot the el cheapo Winchester. The ones that are famous for jamming the 870's. I have shot lots of them. My Beretta A390 likes them. Probably 20 flats. They seem cleaner than the Federals to me.
If I found the Federals cheaper than the Winchesters, I would shoot them even though they are dirtier. I clean my guns after each session anyway.
Just my opinion.