When choosing a speargun, there are many things to consider. First, decide on the type - do you want a pneumatic or a band-powered gun?
Pneumatic guns are powerful weapons that present minimal recoil and allow to make fairly accurate long shots. The diver can increase the power of a pneumatic gun by pumping more air into it. However, if the gun is loaded without a loader tool, its power will be limited to the strength of the hunter. Some pneumatic spearguns incorporate a Hi-Low power actuator that can shut off the main reservoir of air to adjust the gun for close-range shots or simplify the discharging process before exiting the water. As for the downsides, pneumatic guns are noisy when fired, which can scare the fish within the area. It can also be more challenging to aim with this type of speargun, as the shaft exits from the center of a larger cylinder.
Band-powered guns, on the contrary, are much quieter when fired and allow for easier aiming. Guns with open muzzles enable the diver to see the complete path of the shaft. If the hunter wants to increase the power of a gun, all he/she needs to do is add more bands for greater combined power. The bands can be loaded one at a time. Maintenance is also less of an issue with band-powered spearguns. One of the few drawbacks to using a band-powered gun is that the 6mm to 7mm shafts that usually come with them will frequently bend if you shoot a larger fish.
Once you have chosen the type of the gun, you need to decide on the configurations. Some options you need to look at are the gun’s length, type of the shaft, point and muzzle as well as rigging.