Here's a question for you guys. I noticed that the action slide release drops when the trigger is pulled. ...
The Win M12 (and 42) are designed so a short movement forward of the pump action is required to release the slide latch from the action slide inside before the action can be opened after the hammer is fired. Recoil takes care of that during firing. Wear on a used gun can make it seem almost non existant, but the design is there. It's nothing more than a shallow notch in the back of the action slide where the slide latch engages. Pulling the action slide forward a touch allows the slide latch to drop free. Very simple.
Most other pump designs do not have that feature. The slide latch just blocks the rearward movement of the action slide.
(the action slide is the part directly under the bolt and controls the bolts back and forth movement as well as it's cam action into and out of the bolt locking seat).
The slide latch is simply spring tensioned to snap up in back of the bolt slide if the hammer is at full cock. This keeps the action shut when cocked and (usually) chamber loaded.
The bolt is locked in it's locking recess be it in the recv'r or sometimes the bbl extension.
The slide latch then releases either as the trigger is pulled all the way to the rear,,or in some designs when the hammer falls all the way forward. Depends on which gun design, but the result is the same. The slide latch is disengaged just as the round is fired.
The gun is still locked up as the bolt is still in it's locking recess.
Only the manipulation of the pump action will open the action by moving the action slide inside which cams the bolt out of it's locking recess. That is possible as the slide latch has been unlocked by the trigger or hammer motion of firing the gun.
If the action were to be partially open and unlocked, the disconnector in the action engages and though the hammer may fall, it can't hit the firing pin or the firing pin is locked from hitting the shell depending on the design. Even the Win97 has a disconnector in the action for such an event.
All this in a properly maintained gun of course!
Some pumps mostly the earlier pre WW2 had a 'hang fire safety'. Some Stevens 520, all the MArlin hammerless prewar,,,. In those with a dry fire or dud round (hang fire), you have to use the slide latch to open the action. Unlike a M12 where you can just pump the action on a dry fire or dud round and crank another in.
I guess ammo was a bit iffy then!
It's not a bad feature if you shoot a lot of reloads and shoot fast. Might save a second shot over a stuck wad sometime. Makes you slow down and think!