As a longtime paper patcher, just patching tighter will not make reasonable increases in velocity. Check your patches in front of the firing line to see if you are getting blow by. If so, then better wads would be a good start. But your patches will tell a story.

Finer granulation (3f), more powder (and thus more compression, and a different powder (Swiss), maybe better.

What sort of precision were you getting with each barrel using OE? That would not be my first choice for powder.

...never pay Dave "one more dime"