i have the same gun with the 15" barrel and a 4X leupold, i have never had that much trouble even with cheaper factory loads

, the only thing i regret is i wish i had gone with a 2X or varible, i did have a contender in 30-30 that also shot great, my dad has it now, since i bought the encore. and like the others mentioned mike bellm is they man on these dudes, i would say a scope/mount problem also,,
best of luck and welcome to the forums