Have you tried Winchester and Remington rifled slugs?
Rifled slugs do not damage rifled barrels, they just leave a little lead behind that needs cleaning every 20 or so shots.
While sighting in my Tracker II 20g, I got one dead-on bulls eye at 50 yards, from the bench, no sandbags or rest, with Winchester rifled slug. It was the only shot I took where I concerntrated properly and gripped well after I had been all over the place because of the recoil on previous shots.
For $8.75 for 15 rounds, the value can't be beat. Give them a try, no need to spend a bunch on ammo if good quality value ammo is available.
A dead deer doesn't care how much the ammo costs.