[Rainbow Demon]

Around WW1, possibly earlier, infantry weapons designs were tested by submerging the weapon in a mixture of very loose mud and pea gravel, sometimes for up to 48 hours. They then took the weapon out of the mud and opening the action they sluiced away as much mud as possible from bore bd action using one or two canteens of water. They then tested how well the weapon would fire, and if an autoloader kept a record of any malfunctions.

I rather doubt that a milspec 1911 would fail any mud and sand test that a Glock would pass. A commercial clone of the 1911 or a 1911 pistol smithed for matchgrade accuracy might, since these are already well known to be less reliable than the milspec pistols.

As for revolvers, the only time I've heard of a S&W revolver failing in combat was when a friend took a tumble down a mud bank. He was a medic and carried a old police .38 in a old style open topped police holster and gunbelt, his dad had bought it at a garage sale and mailed it to him.
When he tried to fire the revolver at two approaching NVA mud from around the frame fell into the hammer opening blocking the firing pin hole. Luckily mortar rounds dropping all around sent the NVA scurrying or he'd have been dead meat.
Had he carried a cocked and locked 1911 in a similar open top holster the result would have been the same.
There was a 1911 style prototype with enclosed hammer, but they did not pursue that.

Theres alot of places that mud can get into a revolver.
The chamber mouths can collect crud as well.

If properly cleaned and oiled a revolver can lay in a drawer for decades and be perfectly safe to fire.
If not properly cleaned and oiled almost any revolver or autoloader will rust up or be glued shut by a mixture of fouling and congealed oil.
I've cleaned up pump shotguns that were glued shut by old fouling and congealed oil, had to soak them in carburetor cleaner before the bolt would retract. The stuff inside was like half dry black paint.

With modern lubricants congealed crud is less likely, but back in the old days they were not so lucky in available lubes.

PS
If you check old outdoor catalogs you'll see many sporting type hunter's holsters with full or half flap.
A gun intended for carry in the woods was well protected from debris. Now days most seem to think that an outdoor revolver or auto should be carried in a gunfighter type rig then wonder why the pistol ends up rusty or gummed up.
In Canada the mounted police found that tree sap and pine needles could jam a Winchester lever action tight, and even the Lee Enfield failed its first outdoor testing by Canadian militia in sub zero weather due to lack of proper lubricants.