I fired about 20, IIRC, from my new Strike without issue. Its plug is much simpler than the one for my Knight. That one has three different inside diameters to deal with, plus the wire-sized bit. If you let it get crudded up, it's a job to clean, and that crud is hard!
Couldn't you just pull the breech plug and soak it in brake cleaner to soften the crud?
I keep a film can (remember those?) of Hoppes on hand for that. Does brake cleaner work better?
Now that I've got the Strike, with no internal threads on the plug, and (so far) hand removal of the retaining collar, life is simpler. If the Knight stays, I just might go to caps and either Old Eynesford or 777. The Western cap-ignition plug is very simple, much like a Manton breech.
