Usually a barrel swap. Maybe a mag swap. Bolt swap. All depends on what you want to run. Not every caliber is going to run in a standard AR15 lower receiver. 300 Blackout is one of the easiest as it uses the same mags and BCG as your typical vanilla AR in 5.56. Just don't get your mags mixed up (label em).
For my AR pistol in 7.62x39: 10.5 inch barrel, enhanced firing pin, 7.62 bolt, wolf hammer spring upgrade and C-Products magazines. No reliability issues so far and I LOVE it's compact profile.
There's different ways to run 9mm in an AR. Some have a dedicated 9mm magwell while some use magwell adapters for the conversion. I'll let the OP give more insight into his awesome build :).
Usually a barrel swap. Maybe a mag swap. Bolt swap. All depends on what you want to run. Not every caliber is going to run in a standard AR15 lower receiver. 300 Blackout is one of the easiest as it uses the same mags and BCG as your typical vanilla AR in 5.56. Just don't get your mags mixed up (label em).
For my AR pistol in 7.62x39: 10.5 inch barrel, enhanced firing pin, 7.62 bolt, wolf hammer spring upgrade and C-Products magazines. No reliability issues so far and I LOVE it's compact profile.
There's different ways to run 9mm in an AR. Some have a dedicated 9mm magwell while some use magwell adapters for the conversion. I'll let the OP give more insight into his awesome build :).