hello, i am new here and i have a question about the earlier min 14s. my one son has a 181 series made around 1980 with a wooden handguard. it is awesome and functions flawlessly. my other son is looking at an earlier mini 14 made around 1976 and the receiver looks different with more external parts on the left side. are the 181 series more reliable and less complicated than the 180 series? thanks!