Mode of Action

Penetrative stunners cause insensibility due to the concussive blow to the skull and the physical damage resulting from the entry of the bolt into the brain.

Non-penetrative stunners have a ‘mushroom-headed’ bolt which impacts with the skull but does not enter the brain. This type of stunner causes insensibility due to concussive forces alone. Under EU legislation, non-penetrative stunners are only permitted for use on poultry, rabbits, hares and ruminants less than 10kg liveweight.

Method of Firing

Captive-bolt stunners may be trigger-fired or fired by contact with the animal’s head. Trigger-fired penetrative stunners are the most versatile and can be used on a range of different species in different situations, e.g. in abattoirs, on the farm or in a confined space, such as an aircraft. The trigger mechanism may be a conventional pistol-grip (Figure 2) or a trigger pad on the body of the stunner (Figure 3). Contact-fired captive-bolt stunners (Figure 4) are only suitable for stunning cattle which are restrained in a stunning box; they are not suitable for use outside the abattoir on animals which are not restrained.


Figure 2: Penetrative, trigger-fired captive-bolt stunnerKey: Bolt (A), Stop washers (B), Flange & piston (C), Expansion chamber (D), Breech (E), Ejector (F), Hammer (G), Trigger mechanism (H), Trigger (I), Undercut (J), Recuperator Sleeves (K)



Figure 3: Non-pentrative, trigger-fired captive-bolt stunner Key: Cocking mechanism (A), Trigger (B), Breech (C), Ejector (D), Expansion chamber (E), Flange & piston (F), Bolt (G), Barrel (H), Damper (I), Mushroom head (J)



Figure 4: Penetrative, contact-fired captive-bolt stunnerKey: Firing pin (A), Breech (B), Expansion chamber (C), Flange & piston (D), Stop washer (E), Cap (F), Retaining band (G), Recuperator sleeves (H), Stop washers (I), Bolt (J)

In the EU, operators must have a Certificate of Competence in order to use captive-bolt equipment for the routine slaughter or killing of livestock. The use of captive-bolt equipment in emergency situations does not require a Certificate of Competence although it is recommended that operators still seek appropriate training for such scenarios.

The law regarding licensing and certification, in connection with the use of captive-bolt equipment, differs within and between nation states, according to the circumstances. Users of captive-bolt equipment must be familiar with the statutory requirements relating to their particular situations.


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