On my 1853 Enfield rifle musket ( repop) I'm used to swapping out nipples every 500 rounds or so.Symptoms of enlarged apertures are usually , increased breech fouling and a general enlargement of group size.However, how often do you change breech plugs?My Omega's are stainless , which should give decent resistance to erosion of the aperture.I'm using Variflames with CCI 400's with superb results.I used 209's for awhile but noticed some erosion in the plug where the narrow end of the primer seats.Nothing extreme, just looked alittle rough compare to the surrounding metal.The 400's are a less powerful primer so I expect longer life.The owner's manual gives no suggestions on plug replacement so I'm wondering, How often do you change plugs? I was thinking about the 25 ACP plugs , but at $ 59.00 a pop , it seems expensive if the plugs dont last at least 1000 rounds.Any ideas?