Hello guys been hear for a wild now lot of good info (thank you all) this is my curent situation as of now... Dpms upper/lower Magpul fix stock Live in (nj) Cmmg mk3 handguard Dpms lower parts kit Now the money question I'm interested in a criterion 16 inch barrel with the rifel lenth can any on tell me the difference on getting a 18 inch from.....