An Archeotech Revolver is a type of Archeotech Pistol used by high ranking Imperial officials, generals or an AdMech troop like those from the Serberys Raiders. They are by far, one of the most 'common' (Common being used in the loosest terms) types of Archeotech found readily available by Imperial forces. Due to the ancient and simplistic designs of a revolver, these weapons are actually very simple to maintain and construct.
Usually, what's so special about these weapons is that there is usually something advance and wonky in either the ammunition it uses or the barrel itself. The actual firing mechanism is simple, cause, its a revolver. As such, while it fires as per normal, the Archeotech Revolver may have a built-in accelerator in the barrels that turns it into a railgun or the bullet simply phases in and out of reality to hit that son of a bitch. At S5 AP 2 D 2, this thing is leagues ahead of the average Bolter in stopping power, as all things Mechanicus have a tendency to be.
It should be noted that the weapon's offical name is "Archeorevolver" and it has never been given any special treatment in lore outside of being a weapon for Serbys Alphas. The idea it is an Archeotech weapon is fan speculation from it's name. Because GW has never dropped the ball there before.