Energy Source

Cartridge

Cartridges vary in strength and are classified according to the amount of propellant they contain, measured in grains. They range from 1.25 grain for small animals, such as lambs, to 3.0 grain and 4.0 grain for large cattle and mature bulls (1 grain = 0.0648 grams). It is important to refer to the manufacturers' instructions so that the correct cartridges are used for each model of stunner; they are identified by calibre (0.22 or 0.25), colour and headstamp.

Captive-bolt stunners are designed to absorb and withstand high levels of mechanical stress over prolonged periods of constant use. Repeated use of heavy charges on small animals can result in excessive wear on the entire mechanism and premature failure of parts. Similarly, constant use of underpowered cartridges on large animals will result in the mechanism becoming strained and the animals being inadequately stunned. Contact-fired stunners are designed and built to work on a heavy charge only; firing them using smaller charges can lead to inadequate stunning and uneven wear on the equipment. It is therefore essential that the correct cartridge is used for the type of stunner and the size of the animal being stunned.

Compressed Air

Captive-bolt equipment powered by compressed air is limited to penetrative models designed for stunning cattle and sheep. The principle behind their operation is exactly the same as for cartridge-fired equipment, but the energy is supplied via a high-pressure compressor. With air-powered equipment, a higher throughput of animals can be achieved and less maintenance is required. However, the equipment is heavier and less manoeuvrable than cartridge-fired stunners and the animals must be fully restrained.

Refer to the manufacturers' instructions when choosing which cartridge size or air pressure to use.