Here's a vid in the barrel retention system.
Thanks for the video. It's well made. Everything makes sense, They replace the plastic on the bolt. The trigger group cover is in two parts. Replacement barrels are available but not sure if they are made specific for the RPR. Barrel replacement and headspacing does looks easy. Using a different barrel nut like the one with the Seekings handguard works fine. Upgrade to Magpul PRS or any AR stock, Any AR grip possible.