The flash hole in the Omega breech plug i just measured is 0.11" long. Just shy of 1/8" long. If you were to drill through this steel with your 1/8" drill, you would destroy the flash hole, and what was the flash hole would become part of the flash channel. Turning your drill by hand is work just to cut the carbon deposit; drilling steel isn't so very likely.

Being the lazy person i am, i get bored quickly spinning a 1/8" drill by hand, when removing the carbon from a breech plug, used in a long shooting session. This laziness forces me to install the drill in a drill motor, and spin the drill with the drill motor. Once i ended up with a flash hole about 1/32" long, which made me sad, but didn't change my ways. Marking the drill as was suggested, to stop at the proper depth is good. Using a dull drill, makes it harder to drill the steel, and is what i have been doing lately.

Removing the carbon in stages isn't a bad thing i.e. use a 1/16" drill first, or a 3/32" drill, and then a 7/64" drill................

Another thing some have done, is use a 5/32" drill to increase the diameter of the flash channel. This allows more shooting before cleaning is necessary. One needs take care not to drill too deep when doing this.

If you were able to shoot 40 times without cleaning, perhaps you have no need to change anything.