Long time site lurker. First post. Not a lot of mention of the Sig Sauer MPX. Great rifle. Expensive mags but just as good as any custom build. But you forgot one option. Piston driven or direct impingement? The MPX is short stroke piston and I love it. Upgrades. Extractor spring Hiperfire 243G trigger - which may get changed out Sent from my iPad using Tapatalk