The Ballard is quite well protected as far as the action is concerned. However, a punctured primer could possible allow corrosives to enter the trigger area. Since I have never had a punctured primer while shooting BPCR, I doubt that will pose much of a problem.

My BPCR's are a couple of Browning's and one Sharps. They have been shot, literally, thousands of shots. They are still like new.

I use a popular "home mix" bore solvent that is used extensively at Friendship during the NMLRA matches - that is "Friendship Speed Juice". It consists of one pint each of Rubbing alcohol, Murphy's Oil Soap, and Hydrogen Peroxide. You can find all ingredients at your neighborhood super market or drug store. It is quite inexpensive. It absolutely dissolves black powder fouling on contact. Two or three wet patches and then a couple of dry ones and the barrel is clean. You MUST then follow up with a wet patch of your favorite protectorant. If you use a commercial product I can recommend Birchwood Casey's "Sheath" or "Break Free". I, personally, use another home mix product, "Ed's Red". I then wipe off the whole rifle with my protectorant being careful to keep it and the previous solvent off the wood (most good bore cleaner's will tend to soften wood finish if left on the surface).

The full story on "Ed's Red" can be found here:

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As an ex-soldier during the corrosive ammunition years (yeah, I'm that old), the old army directive of visiting your rifle three days later with another wet patch of your protectorant (in my case, Ed's Red) is a good idea.

It is not a bad idea to also run a few drops of protectorant along side the breech block and operate the action a couple of times to distribute it.

Browning recommends that you spray WD-40 into the action after the cleaning process. Probably not a bad idea, either. However, you do want to be careful to NOT oil or solvent soak the wood. This will lead to the early demise of your stock - NOT GOOD!

Dale53

David, I did warn about potential wood problems with spraying the action. An easy solution would be to simply remove the wood (on a Browning) before you spray. Then let it drain overnight before re-installing the wood. If you only do it a couple or three times a year, it shouldn't present a problem. I have a number of rifles that I would not be interested in removing the wood due to the possibility of "wearing out" the wood threads in the stock. However, a Browning has a thru-bolt and this should not be a problem. If you flush the action two or three times a year, even that shouldn't gum up anything. 

Naturally, if you do the "spray once and never re-visit" I would expect to get exactly the same results that you have experienced.

YMMV
Dale53