I’ve heard so many opinions on barrel length but I’ve often felt like the opinions were not confident or lacked depth of explanation. In my quest for factual answers, I found the video below. It’s extremely detailed and offers the best explanation that I’ve seen. It’s not that straight forward though, if you’re looking for a simple answer. It really depends on your situation and mission objectives.
What it comes down to for me, is if you need it for CQB and getting in and out of vehicles, then a shorter barrel is more manouverable but may lose accuracy over 100 meters. If you need it for long distance, then a rifle with a longer barrel is more accurate. As the video states, the type of ammo you use makes a big difference to the velocity and fragmentation, regardless of barrel length.
In a South African tactical security context, I have used both long and short barrel rifles. I will train with and use whatever I’m issued, however I have seldom been placed in a static position that required me to aim as far as 100m. Getting in and out of a vehicle with a long barrel for tactical debus is a nightmare.
In my opinion, unless you’re a sniper, the shorter barrel is better for most security work in South Africa. If the threat is violent crime, protecting a community is usually done from a close distance or in a response capacity. It usually involves getting in and out of vehicles and moving through buildings. Protecting people from violent crime that occurs in terms of home invasions, hijackings and armed robberies, normally requires a close range.
The only context where I have preferred a longer barrel for increased range has been large communal events, where the assessed threat has been terror attacks from a distance and there I have sometimes preferred a longer barrel. I guess what it comes down to is that it all depends on the application as it pertains to the threat and your security role.
Sometimes it’s actually irrelevant as you get issued what you get issued by the company you work for. You have to work with what you’re given, so make sure you can operate whichever rifle you’re issued as well as you possibly can.