So I have an original xcarry and the barrel from it will not fit into my v2 model, it’s almost like the chamber is to long. No matter what I do the barrel will not lock in. My understanding is that the original models had fitted barrels or something like that. I believe C&H has a service for this model to mod barrels for use in the v1. Also since the v1 is only drilled for a Gen 1 Romeo they offer a service will drill the slide to work with an rmr / holosun. I sent mine to C&H and had a sig threaded barrel modded and the slide drilled and turned it into a comp build. Works great.