What is the correct headspace location for rimfire cartridges?

The correct headspace location for rimfire cartridges is at the rim of the case. Headspace in firearms refers to the distance measured from a specific point on the cartridge to the chamber of the firearm. For rimfire cartridges, this specific point is the rim, which serves both as a support for the cartridge and as a surface for the firing pin to strike.

In rimfire cartridges, the priming compound is located in the rim, which is why the cartridge relies on precise headspace at this point to ensure reliable ignition. Accurate headspace allows for proper alignment of the cartridge in the chamber, helping to maintain the ideal distance between the base of the cartridge and the bolt face. This is crucial for ensuring the firing pin strikes the priming compound effectively, allowing the round to fire consistently.

Other choices represent different points that may be relevant in the context of centerfire cartridges or general cartridge design, but they do not apply to rimfire ammunition. For instance, the top of the belt of the case or features located at the shoulder are more pertinent to centerfire cartridges, where headspace measurements are taken at different points due to their design and function. The leading edge to the mouth also does not pertain to rimfire ammunition as it does not get