Hello Ron, Does this photo show what you are looking for? The light direction from right and shadow may be an issue. FWIW when I mounted a new scope with these rings windage was nearly spot on at 25 yards.
Some center fire rifle shooters use fire lapping to smooth out barrels using polishing compound in grease grooves of cast lead bullets. These are shot at lower velocities. May be a crazy idea for air rifles.
Thanks for response. I live in US. Am not familiar with “Wes”. Also what is source for longer barrel? My PCP experience in only .25 Marauder tuned by Tim Hill.