Vent liners are used to replace the flash hole.

Zeak the vent liners here are used in a modified CVA breech plug that Ron designed. Replacing the vent liner is far cheaper than buying a new breech plug when the flash hole erodes (wears out).
A very excellent idea. And a great post here Ron.

Excellent Post and tutorial !!! great work with awesome results.

Ken

I prefer Ron's vent liner plugs in both my Optima V2 rifle an pistol, they just plain work! Not to mention are so much easier to cleanup than the regular BlackHorn plugs!