https://www.calguns.net/ Centerfire rifles, carbines and other gas operated rifles. en Fri, 10 Apr 2026 03:36:48 GMT vBulletin 60 https://www.calguns.net/images/misc/rss.png https://www.calguns.net/ https://www.calguns.net/forum/firearms-discussions/centerfire-rifles-semiautomatic-or-gas-operated/54871830-question-about-sig-mcx-300-blackout-upper Thu, 09 Apr 2026 04:04:18 GMT
So I recently purchased a sig mcx-r regulator in 5.56. I've heard you can put an mcx .300 upper on them. Anyone have any info on where'd I could get a legal length .300 upper for it and what issues I might have ? ]]> Centerfire Rifles - Semiautomatic or Gas Operated Nego https://www.calguns.net/forum/firearms-discussions/centerfire-rifles-semiautomatic-or-gas-operated/54871830-question-about-sig-mcx-300-blackout-upper