I have a Glock 21 and love it!
ALL my pistols have kydex holsters (Vedder & Safariland). My 21 uses a Safariland OWB with weapon light. My other pistols use the Vedder LightTuck AIWB.
If the gun is holstered when put on and taken off, there is no problem with an AD. JMO
The only time the gun should leave the holster while wearing when loaded is if it has to be used to save your life!!
You practice drawing with an unloaded weapon!

Be SAFE and Shoot Often!