What does a wheel lock firearm utilize to ignite its charge?

A wheel lock firearm operates using a unique mechanism that involves a spinning wheel to create sparks. When the trigger is pulled, the wheel, which is a metal disc, rotates against a piece of iron or steel, producing sparks. These sparks ignite the powder charge in the firearm. This ignition method is distinct to wheel lock systems, making them recognizable in the history of firearm technology.

The other options reflect different firing mechanisms found in various types of firearms. A cap with metal foil is associated with caplock firearms, where a percussion cap is used to seal the ignition charge. A spring-loaded hammer is typical in modern firearms, where the hammer strikes a firing pin to set off the round. A straight pull trigger is a feature found in some rifles that allows the shooter to cycle the action without a traditional bolt mechanism, but it is not related to the ignition method used in a wheel lock system. The core characteristic of a wheel lock firearm is its reliance on the mechanical spinning action to generate ignition, which is why it distinguishes itself from other mechanisms.