Hi Geoff, do those regs sit internally in the tube or are they added at the end by the block?. I'm wondering whether this change might be inducing POI change in relation to cylinder pressure, possibly moving the barrel a gnats?

It can happen with Steyrs where the barrel goes through the 'A' frame.....quite a few FT/HFT shooters have opened the 'A' frame hole slightly as some were getting POI changes related to cylinder pressure and/or temp changes.