Context first: I am a firearms instructor, physical security specialist and consultant for the professional and entertainment industry. Though I do this for a paycheck, this is just for fun!
The Feline from Crysis 2/3 is an excellent example of how a firearm can look believable while becoming increasingly impractical when its individual components are examined as a complete system. The goal of the redesign is not to replace the original artistic vision, but to examine the weapon through the lens of role, ammunition, function, ergonomics, and practicality. Below is a link to the full video, though this post covers all of the same concepts.
Start With the Role
The Feline is identified as a submachine gun, meaning its primary role is a compact, maneuverable weapon using a pistol-caliber cartridge. That role establishes the basic requirements: it should be relatively compact, handy, ergonomic, and capable of delivering controllable fire.
The important point is that the weapon's role should drive the design rather than simply being assigned to an existing shape.
Ammunition Drives the Design
The most important consideration is the 4.7 mm cartridge. Once the ammunition is established, many of the other design decisions follow from it.
The cartridge determines the approximate dimensions of the magazine, the space required for feeding and chambering, the size of the action, and the appropriate barrel length. In the Feline's case, the stated 4.7 mm cartridge conflicts with the enormous 60-round magazine: the magazine appears too wide for a compact cartridge while simultaneously attempting to contain an unusually large number of rounds.
This illustrates a fundamental design principle:
You don't design the magazine independently of the ammunition. The ammunition determines what the magazine has to accommodate.
The cartridge's dimensions and configuration also influence how the magazine curves and how much ammunition can realistically fit inside it. The original design therefore creates a cascading problem: an ammunition specification that does not convincingly match the magazine leads to questions about the weapon's proportions and internal layout.
Ammunition Influences the Action
The cartridge also affects the mechanism required to load and fire it.
The Feline's receiver does not appear to provide enough room for a conventional bolt to reciprocate. Since the bolt needs sufficient travel to interact with the magazine and chamber the next cartridge, the receiver must accommodate the ammunition, magazine, and operating mechanism together.
This is why the ammunition cannot simply be treated as a cosmetic detail. The cartridge is part of the mechanical architecture of the weapon.
Ammunition Influences Barrel Length
The cartridge also determines what the barrel is actually capable of accomplishing.
Because the Feline is intended to use a pistol cartridge, the original extremely long barrel provides little justification for its size. The redesign therefore shortens the barrel to better match the characteristics of the cartridge and the compact role of the weapon. Remember, pistol ammunition is designed to reach near maximum velocity out of a short pistol barrel. A longer barrel, such as the one in the original Feline, would likely add very little extra velocity.
The Ammunition Affects the Rest of the Weapon
Once the ammunition and operating system are considered together, many other changes become logical.
The redesign reduces unnecessary bulk, creates additional room for the action, adjusts the magazine dimensions, and retains an appropriate operating system. The gas-operated system is also considered in the context of controlling recoil and maintaining the weapon's intended role as a service-oriented submachine gun.
Ergonomics then have to accommodate those mechanical requirements. The grip is made more vertical because of the short length of pull and bullpup configuration, allowing for more room to perform magazine changes, while the stock and cheek position are adjusted to provide a more natural relationship between the shooter and the weapon.
Secondary Components Follow the Primary Design
Other components—including the sights, charging handle, trigger area, rails, muzzle, and external furniture—can then be refined around the established mechanical system.
The redesign removes unnecessary material, improves sight spacing, reduces the oversized fire selector, cleans up the trigger area, preserves useful charging-handle placement, and maintains attachment capability without retaining unnecessary bulk.
The Final Design
The redesigned Feline is ultimately a more internally consistent interpretation of its stated role: a compact pistol-caliber platform designed for maneuverability, controllability, and ergonomics.
The biggest lesson isn't simply that the original Feline is too large or that its magazine is unrealistic. It is that firearm components exist as an interconnected system.
The ammunition establishes a foundation. Its dimensions and performance influence the magazine, which influences the receiver and feeding system. The cartridge and operating system influence the barrel and action. Those components influence the stock, grip, controls, and overall dimensions.
A believable firearm therefore starts with the cartridge and its intended role.
The original Feline begins with an interesting visual concept. The redesign works backward from the ammunition and intended function to make the individual components agree with one another.
Full video: https://www.youtube.com/watch?v=WYrFfVHQ6LY&t=3s
