The left hand of the two is a phoshor bronze replacement for the plated brass original on the right.
The two problems with the original are
(i) only 2 turns of thread engagement into a cast zinc body of a 12mm OD holding against 800psi
(ii) the product is now obsolete rendering all parts low stock or unobtainable.
My replacement uses the full thread depth in the frame giving better engagement on a previously partially stripped thread (& so scrapped target pistol) than OEM, to achieve full thread depth a mechanically retained, off the shelf O ring replaces the OEM plastic seal.
The whole job is milled, apart from polishing ;-)
P.S. A big thanks to a great forum for the help and support that's helped me to get from no experience of CNC to here in around 12 months