>>574394
I think that if level IV armor continues to get cheaper and lighter we will eventually need a new projectile to defeat armor. At first armor penetrating bullets will be used, but I think the future will be in creating bolter shells. Let me elaborate on why:
When defeating tank armor, militaries originally used velocity dependent rifles to defeat armor. As the armor improved, the rifles needed to become bigger, and required recoil reducing measures to be able to be wielded. Armor on tanks continued to improve until no armor piercing rifle could defeat them. This is when RPGs, LAWs and other rocket weapons replaced them. Instead of using a velocity dependent system, we used a velocity independent explosive.
The current solution to defeating body armor is a velocity dependent anti-armor bullet. This means range is limited and as the armor gets stronger, special materials will be required, such as tungsten. Requiring special materials for common items like bullets is a problem, because special materials are not only expensive, but in short supply.
When weapons such as medium machine guns are no longer effective, or require special material bullets, militaries will be searching for a cheaper solution. Such a solution will be use of an explosive, given that explosives are much easier to make. However, delivering an explosive to a target with a conventional bullet is difficult. Propelling the explosive up to the velocity required to cover distance means heavy recoil on the shooter.
The solution to this problem is to use a gyrojet. The original gyrojet system was not intended to be an explosive payload delivery system, but rather to be an alternative to lessen the need for quality barrels. It never caught on because of two problems: 1. gyrojets needed time to reach a high enough velocity to be deadly. 2. gyrojet cartridges were expensive to produce due to complexity.
To address problem 1 in this situation, by utilizing an explosive in the tip of the cartridge, the gyrojet is effective at any range or velocity. Furthermore the system can be hybridized, utilizing a short period where the bolter is fired from a cartridge through a small closed barrel, giving it an initial velocity before it begins to travel on its own rocket engine.
To address problem 2, with the availability of automation and CNC manufacturing, manufacturing anything complex becomes inexpensive once the startup costs have been handled. Bolter shells will not require any rare or expensive materials, their cost is entirely based on the manufacturing work required to make them precise. While getting an assembly process in place to make them consistently will take time and likely millions of dollars, once the process is complete the unit cost will continually drop until it is barely over the cost of materials. Given that a military has need for a large volume up front, this means an immediate drop in the per unit cost opposed to if the system were offered to the public first.
Furthermore there will be secondary benefits to this system: Not being velocity dependent means that combining infantry and LMG cartridges into one will be more feasible without the cartridge debate. The weapons themselves will be able to be simplified to blowback, as most of the velocity is developed outside the barrel, improving reliability and dropping weapon cost. Weapon noise will drop, allowing for better unit communication.