I'm not an expert, but the same payload, at the same velocity should equal the same recoil. The pressure is another matter.
Pressure has no relationship to recoil.

I am not sure why this thread is going on in 2 sections? I think perhaps the biggest difference in the felt recoil has to do with shell length and chamber length. The federals are a little longer and it may be why I noticed more recoil.

There are other variables at play in all of this as well. Some wads absorb up some of the felt recoil better than others(RSTs are using premium wads). I would think the burn rate of the powder plays an important roll in terms of velocity, recoil and overall performance.

Those 2 1/2' RSTs at 1200fps are nice shells. They were easier on me, and my 112 year old gun...and they are faster than the standard 16 2 3/4" 1oz. load.

Jay, I can't figure out how to delete one of the threads.