Interesting discussion, causes me to wonder if their intended real purpose may not have been to act as a deflection devise for escaping gases in the event of a punctured primer, much as some standing breeches have a gas escapement groove cut in them. Fences served a similar purpose on earlier guns as a form of protection for the shooter.
Anyone know where side clips originated or what gun was the first to tout them? Was there ever mention of them being 'protective' or was it always advertised as being a 'lock' or bolting improvement?
Personally, I find them an annoyance & have suffered a cut on more than one occasion from being inattentive.
