the Mossberg ATR100 is a good solid rifle, well made and pretty danged accurate. as mentioned, they do have some stiff recoil. i highly recommend them for a hunting rifle, but not for target shooting.
when i had mine a few years ago, with handloads, mine was very accurate. Mossbergs have a solid reputation. the only reason i traded mine was because of the recoil. i tried different things but just couldn't soften up the felt recoil. if you can handle the recoil, then you will be pleased with the rifle.