A while back i purchased breech plug & adapters from Precision Rifle. They worked good. My first surprise was how little blow by there was around the adapters. . My second surprise was how clean large rifle magnum primers burn compared to shotgun primers. My third surprise was how the rifle primers don't erode the flash hole. After many shots there started being more and more blow by around the primer adapters. This didn't surprise me. This same thing always happened to me whilst using shotgun primers. To this day, it still surprises me how the rifle magnum primers do not erode the flash hole. Compared to the rifle primers, shotgun primers seem to be mini sandblasters.

After the breech plug started leaking a bit of soot around the primer, i started thinking about the possibility of using an o-ring. Looking around, i found an o-ring i thought might work. It is 1.5mm thick with a 4.5mm ID, which makes an OD of 7.5mm. Some of these o-ring were ordered, along with a 7mm end mill. One thing i wondered, is if the flash hole of the breech plug didn't erode, because of the material it was made from. So.. i decided to modify an OEM Omega breech plug to use the PR adapters. This involved enlarging the flash hole from 0.029" to 0.032", because this is how the PR breech plug came. When the end mill, and the o-rings arrived, i used the mill to enlarge the primer socket in the Omega plug to utilize the PR adapters, and the o-rings.

Now, after two hundred shots, i 'know' shotgun primers are very very much like a sand blaster. My 'homemade' breech plug now has 207 shots through, and the flash hole which was made by a 0.032" drill, now measures 0.032". Large rifle magnum primers are so very very much 'gentler' on breech plugs. Had i been shooting shotgun primers in this breech plug, the flash hole now would be in the neighborhood of 0.037", or thereabouts.