Waffling again Musket, or is it Muskets:

First you are talking about target or clay pigeon shooters - then onto bolt action hunting rifles - and now you are talking about your vast experience with a semi-automatic assault rifle.

Shotguns of which there are a vast array of makes and models. But we will take three basic ones:

Break Action (Can be side-by-side or over-and-under) to load you must break the gun open, load two cartridges and in closing the gun you automatically make it ready to fire.

Hammer Lock Either single barrel or side-by-side this gun too breaks as for the Break action type but with this gun after loading and snapping the barrels back into the closed position to make the gun ready for firing you have to "cock" the gun by pulling the hammer or hammers back

Pump Action single barrel with a three or five round magazine the gun is loaded by loading the magazine then pulling the slide back (loads the gun) then pushes the slide forwards ("cocks" the gun)

Now ask all three owners of these types of weapon to "cock" their guns and they will do three completely different things. Of the three types of shotgun you can always instantly tell when a Break Action or a Hammer Lock Shotgun are "safe" - Without close examination of a pump action shotgun it is impossible to tell if it is "safe".

Now then Muskets your tale of the 7.62mm SLR and "Your Rock Ape" (RAF Regiment - Drill Sergeant no doubt). The SLR was a semi-automatic weapon on returning from anywhere where you have had a magazine attached to the weapon every man will individually be asked the "Prove" his weapon safe:

1: Magazine off the weapon
2: Pull working parts to the rear to cock the weapon
3: D.I. may physically check the chamber by sight and by feel to ensure that the chamber is empty (returning to an armoury after a ceremonial parade or after drill)
4: The rifle is then pointed muzzle down into a sand pit or barrel and the trigger is pulled bring the working parts forward - the gun should just go click as it has just been "proven" safe - If it goes bang then you are deeply in the shit (hostile or active service returning to base after a patrol)
5: Enter base keeping the weapon with you if on active service or if not return the gun to the armoury where it is stored in an unloaded safe condition with the working parts forward i.e. "uncocked".