One thing I can say is.......everyone that takes the time or is aware enough to know their guns shooting blackpowder and clear them of any fouling or oil are dyed in the wool shooters extrourdinaire. True blackpowder afficionados.
They won't be telling any whoes about the BIG BUCK that stood there watching as the hunter looks at his gun wondering why it didn't fire and make meat.
No matter what the method if it results in a gun ready to fire then it's good.
When I pratice with my "Hawken" rifle I need to clean between every two shots. The five hundred grain lead bullet(Lymans mould Govt. bullet) is long and fits perfect in the barrel. It's put thru a swag that imparts the rifling to the bullet so it's possible to load it at the muzzle. The fast twist(1-20) of the 45/70 barrel(nice 4140 ordanance grade steel) makes it even harder to load if the barrel is fouled much at all.
If I don't run a damp patch then a dry one every two shots the bullet can stick part way down the bore. Trying to ram it home obsturates the lead and makes it even tighter. Then it takes a steel rod centered in the bore to drive the bullet down on the powder. Just something I'd rather avoid. That's why I like to damp patch the bore every two shots at least.
The wiping action can push fouling down over the hole of the flash channel in the powder chamber of the breech plug. It's then that I need to clean the nipples hole and flash channel by firing a cap or two or three. That's to avoid the misfire when the flash hits the damp fouling blocking the flash channel in the breech plug.
That said I can sadly say...the debris from the caps sometimes blocks the nipples flash channel. I blow thru the muzzle to try to clear it. If that doesn't work then off comes the nipple and the pipe cleaners come out to clean the channels. Then a little powder put under the nipple before screwing it back in to help with the load firing well next try.
Before I hunt with the gun it's cleaned as well as I can metticulously do it. No oil, no rust, no anything but dry steel anywhere where the load chain goes.
That means no caps snapped to clear the channels.
I'd be afraid of the cap debris causing a misfire when I have a nice buck in the sights. If I did snap a cap then off comes the nipple and out come the pipe cleaners again to brush out the channels.
The only thing in the clean dry steel barrel when I step into the fields or woods is the load chain with the bore above it lightly lubed for rust prevention. Even with a sealed bore and nipple area(sealed as I always do since it'll always rain or spit wet snow during the deer season) there can develope slight rust in a really clean bore from the air in the barrel.
I can't tolerate anything that might cause a misfire and......snapping caps to clear can leave debris in the nipple. It's that little round flat burnt disc left from the caps ignition chemical that blocks the nipple. I see it whenever I do snap a cap. I usually have a needle in my little doeskin bag of little tools to pick that danged little piece of burnt disc stuff out of the beginning of the nipples cone.
So......I figure it may be my gun and the way it's hammer hits the nipples cone flat and perpendicular to the nipple or.....any caps I ever tried can leave some "stuff" in the nipples cone area.
I've seen it so many times in so many different blackpowder guns nipples from snapping caps I can't be fooled to think snapping caps is a good way to clear the flash channels in the guns. If anyone does they at least have to check to "see" if that little burnt disc of debris is there blocking the flash channel. If it is.....blow thru the muzzle or pick it out with a needle.
Snapping caps can block the flash channel. Pure and simple.
Be like me and be an ,"almost wise old man", and check to see if the snapped caps leave the debris.