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== 580 and 180 series Mini 14 ==580 and 180 series Mini 14.* http://rugerforum.com/phpBB3/viewtopic.php?t=112068Ruger's signts on their 580- guns are probably a lot better than the old series (including protected post front sight), and if you get a .223 with a serial number above about 580-50000 it will have a heavier contour at the rear of the barrel....which is better for accuracy. If you're going to mount a scope you'll be best off with a Mini-14 Ranch Rifle - they have scope ring attachments forged into the receiver.The differences between thr 580-581 series: the receiver contour is different. The barrel is different. The buttplates on the stocks are different. The sights are different. The rear sight in particular, is different in function. It has an aperature on a post that screws in or out for elevation adjustments and is moved left to right in a track by opposing screws for windage. The twist is 1 in 9". Others have been 1 in 7", 1 in 10" and 1 in 9" also. Supposedly the tolerances have been tightened on the 580,581 series for better accuracy. Supposedly part of the inaccuracy problem of the old rifles was due to the front sight being pressed on the barrel which sometimes bent the barrel a little. the new sight is a better protected post, not pressed on in the same way. The 581 and later 580 series (in .223) had a tapered barrel which is thicker at the gas block and thins toward the muzzle. The early 580 series had a barrel of the same diameter ahead of the gas block. Get the tapered barrel, they changed it for a reason. Don't be confused by 580, 581 series designation, when they get to 99,999 in the 581 series, it will become 582 series.