I thought Glocks had an external safety in parallel with the trigger. You want another safety?
I use the safety on my H&K during administrative manipulation/unloading. It's a DA/SA and I keep it in Condition Two, chambered, hammer down, safety off.
I use the safety on my SA1911A1 as it is intended, in Condition One, chambered, hammer cocked back, safety on.
I do not use the ineffective safety on my Luger that I keep chambered, not cocked, safety off.