Can't hurt to try - go ahead and have fun
The more common experience is that there is no useful velocity gain - many people aren't even trying for a velocity gain with moly but for more shots between cleaning and/or easier cleaning as when shooting is hot and heavy on prairie dogs or ground squirrels or the blacktail jacks, may their tribe increase, if they ever come back -
Most people find that moly over copper fouling is a bad idea including increased corrosion - there is some dispute as to what impurities in moly compounds, if any, might be hygroscopic, there is no dispute that moly in a previously fouled barrel is a bad idea - sort of like cast bullets apparently it pays to get the barrel really clean before laying down moly - then apparently whatever moly is removed by a shot is replaced by the same shot for a steady state effect - similarly most people find that a moly coated barrel without the moly bullets is a bad idea as the barrel corrodes while the moly is shot out unevenly and so each shot is done with unique conditions where consistency is the idea in a varmint rifle.
My own experience is that there is nothing to be gained by hotrodding a .22-250 with a 55 grain bullet - as others have said when you need more than a .22-250 with a 55 grain bullet you need a faster twist heavy bullet or a 6mm not a .22 Swift. No reflection on a .220 Swift but do the math to figure out just how many yards the faster bullet out of a maxed out .220 Swift travels before it slows to .22-250 muzzle velocities and figure the .220 Swift will range the .22-250 by no more than those few yards. Then figure what the gain is by hotrodding the .22-250.
