In general, every product when it is designed has a programmed useful life. The life cycle of an equipment starts from the moment it is acquired until the decommissioning. In general, this cycle consists of four phases: Acquisition, Deployment, Operation and Deactivation.
As with all industrial processes, maintenance is one of the steps that allow determining and extending the life cycle of equipment. An example of this is a considerable number of aircraft designed for World War II, which are fully operational today exceeding their useful life.
There are several ways to measure product life. In the case of machines the most common is the number of operating hours (airplanes, tractors, locomotives … etc.), In the case of cars the most common is for miles driven.
But when it comes to firearms and their AR 15 loader, what is their useful life?
It asks in a taboo way, since there are not many sources of research. It is often and common to say that: “this weapon has been in the family for generations”, or that “my weapon will be used by my grandson”, “imported weapon lasts a lifetime” … etc.
But if we think rationally, the reality is quite different. Deep down we know that the weapon is just a “refill” for ammunition.
Of course, there are many variables such as: its initial design in the factory already stipulates an ideal cycle of useful life (in the case of weapons it is not informed), its intensity of use, cleaning, maintenance, lubrication, quality of materials… etc.
Since firearms are basically made of metal, an ever-present factor is that it goes regardless of its use – metal fatigue and mechanical fatigue.
Metal fatigue: A cumulative effect that causes a metal to fail after repeated stress applications, none of which exceed the limit stress force. Metal fatigue is the stress that causes failure after a specific number of cycles. The number of cycles required to produce failures decreases as the heat of tension or stress increases. Other factors such as corrosion also accelerate the metal’s fatigue state.
Mechanical fatigue: It is the phenomenon of progressive rupture of materials subject to repeated cycles of stress or deformation. The study of the phenomenon is of importance for the design of machines and structures, since the vast majority of failures in service are caused by the fatigue process, about 95%.
Cumulative cycle of stresses, under high pressure and temperature, plus the deficient lubrication system is quite simply a test for metal and mechanical fatigue.