Yep - The barrel harmonics on the early models (18X serial numbers) was horrible - thus, the "accu-strut" being used by many to correct for this and get better accuracy. Ruger re-tooled production in 2003, IIRC. The post re-tooling models (580+ serial numbers) don't benefit from the strut. I've found my later model to be just as accurate as my basic no-frills AR.Minis had a reputation for mediocre accuracy for years. The problem was traced to poor barrel harmonics. Once that was addressed in production the issue went away.