News flash. You only need high level for endgame activites. Anything lower level doesn’t affect your effectiveness. Therefore, use the guns you like, until the pieces you infuse into them would bring them up to a level at with you would be able to step foot in the activity you want. Furthermore, raising 1-2 levels on one piece or even 2-3 pieces won’t make a difference in your ability to clear a given activity, assuming you are borderline light level. Smart infusion doesn’t have to limit your loadout options.