Peak pressure will be similar in both guns, as peak is hit before the bullet leaves a revolvers forcing cone, but the revolver bangs bullets around a bit more than a rifle, and with the short barrel developes less speed than a rifle. So if both types of gun had identical barrel quality, the rifle will be able to shoot non gas checked bullets at much higher velocity than the wheel gun. The best I've seen, in a very well lapped and polished 444 Marlin, was 2450 fps using my WFN 280 gr in bevel base. That load would print an inch at 100 yards consistently, here in cool Idaho fall weather. Most rifles with a reasonably smooth barrel, (lapped) and chambererd for the revolver cartridges, will drive ungas checked bullets, lubed with LBT bullet lube, to1600 to 1800 fps with excellent accuracy and minimal or no leading. When loaded to the limit for cool weather shooting, if one snaps off several shots rapidly on a much warmer day, he'll get some leading and severe accuracy loss with non gas checked. Not to worry, let the gun cool to the ambient temperature where you got no leading and a few shots will clean all the lead from the barrel. ONLY with LBT bullet lube though. If you lead a barrel with any other lube that I'm aware of you'll either have to shoot it out with gas checked bullets or use elbow grease and solvent.
Your 320 gr will probably work beautifully with the gas checks left off, in both guns, if the bores are good. At worst, just back off on the charge a little when the bullets don't have the diaper on. You'll save the cost of the check plus a little powder, which is the main reason for wanting to get along without gas checks. Try it with your full loads first though, as changing the charge will require a sight change with both guns. Better to let them both lead a little and give up a bit of accuracy when shooting without gc's, then trip off a few gc loads at the end of the shooting session to clean the barrel of any lead.
