Don't use those factory ammo charts tell you how a certain cartridge preforms. That is just their stated ammo not what it is capable of. The .220 swift has 3.18cc case capacity while the 22-250 has 2.75 so yes the swift can be loaded hotter then the 250. They are both very good caliburs and both preform well. I have had both and I chose the swift for a number of reasons but the main one wasI love loading for it.It has been the most compared to varmit rifle years. I think if a guy had a .22LR ,.220 swift, 30-06, 45/70 and a 12 guage you would have all the long term ,most talked about , the ones everyone is trying to improve caliburs in the buisness.
Getting back to the subject, There are alot more factory ammo offerings for the 250 , hornaday's 40 vmax rounds are pretty awsome out of the swift, 4200fps while the 250's are 4150fps. I can take that same bullet and push it at 4400fps(Accur 2520 42 grain) loading it on my swift ,but I could only get about 4200fps(Accur 2520 38.5 grain) out of the 250. So there is some useful info for ya not based on the fact I own one or the other.But like I said they are both very good rounds. If you want to know I have a Ruger M77 MKII target .220 swift, andhad that same rifle in 22-250.Good luck !!!!!