Don’t trust them

[Keb]

Shoot it out 4ffffg either in the touch hole or under the nipple.NEVER in reach the plug unless absolutely necessary. Lots of gremlins under that plug waiting to bite your butt.

I've made a few Guns, installed quite a few breech plugs and done a lot of shooting in my time. I'd not be afraid to unscrew a breech plug in any "custom" American made barrel. Shooting out with 4f powder is difficult with a flintlock gun, not so much with percussion. However, I've not pulled a breech plug of a foreign made barrel knowing they do strange things on their barrels so your caution is noted, Professor. In the end, experience is the best teacher.

 

[hanshi]

I've pulled the breech plug from my .40 Lancaster on a couple of occasions. A bit of pitting in a 1" section of the breech made this necessary. I had no trouble doing it even though I'm all thumbs.