Good call, Al.I've often thought that it sounds a very strange term. To "break" the barrel almost implies that you are making the barrel non-operational!
The terms are stuck with us now, though, and I can't see the description changing. Even if any new naming was employed on here we're just a tiny part of the whole community.
And when it comes to the various propulsion systems, it does seem stranger to me that the CO2 guns come under the airgun umbrella when they're using a gas other than air. In that respect, that old author was more on the money.