I guess we just all prefer to promote safe shooting practices MD. "Cap blow" isn't the only bad thing that can happen with sidelocks as I am sure you well know. I've seen guys loose an eye from hammer spurs blown off from extreme blow back and other such rare but yet still occurring instances. Safety glasses would have saved them more than likely. You wouldn't see me get anywhere near a flint lock without my amber wrap around shot gun glasses. Many many moons of experience have taught me that pretty much anything can happen when it comes to firearms and the best way is always the safest way.