I don't intend to start an opinion war, but here is another opinion I found on "Ruger Forum.net" when I looked for an answer to a dirty primer pocket causing primer ignition failure:
"Dirty primer pockets are often the cause of a miss fire due to the primer legs not seating on the bottom of the pocket because of crud. A Lee primer pocket cleaner that does large and small pockets cost me $2.99 and is money well spent for relyable ignition. A large percentage of miss fires can be fired if cycled again because the first hammer fall seated the primer."
I don't know what 0.002-0.003" of carbon deposit looks like inside a primer pocket, but isn't it reasonable to assume that might be enough to prevent a proper seating depth of the same size on the rare occasion (in my experience) that a primer fails to fire the first time it is struck?
"Dirty primer pockets are often the cause of a miss fire due to the primer legs not seating on the bottom of the pocket because of crud. A Lee primer pocket cleaner that does large and small pockets cost me $2.99 and is money well spent for relyable ignition. A large percentage of miss fires can be fired if cycled again because the first hammer fall seated the primer."
I don't know what 0.002-0.003" of carbon deposit looks like inside a primer pocket, but isn't it reasonable to assume that might be enough to prevent a proper seating depth of the same size on the rare occasion (in my experience) that a primer fails to fire the first time it is struck?