Haven't really felt the need to use an O ring in my Accura too much, but here is what i did to the worn Omega breech plug pictured.
This breech plug has seen many rounds, and also has been modified and fitted with a savage vent liner. It hasn't seemed to be as accurate as a new unmodified breech plug, so i figured i would toss it.
Screwbolts suggested i drill the primer pocket deeper using a letter C drill which would allow the use of an O ring. I tried using an O ring in the damaged breach plug without drilling it, but couldn't get the action to close. So, i followed
Screwbolts advice; purchased a letter C drill, and drilled the primer pocket some deeper.
Here is what the breech plug looked like with the O ring installed. It fits nicely, and doesn't want to fall out. The O ring is 1/4" outside diameter; 1/8" inside diameter, and 1/16" thick.
This morning i headed up in the hills, and fired 7 shots with the Omega, and the modified breech plug, with an O ring installed. The load was 105g BH209, a 300g 44 caliber xtp, a Harvester crush rib sabot, and a Federal 209A primer. Following is a picture of the 7 spent primers, and the used O ring as well, along with a new O ring.
One can see there is zero blow back when using the O ring.