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M36 Rifle

Operation: Select-fire, gas-operated, magazine-feed, ETC

Mass: 2.9kgs (unloaded) 3.5kgs (loaded)

Barrel Length: 50.8cm

Cartridge: 6.8x31mm caseless

RoF: 500rpm (3r) 1800rpm (full-auto)

Effective Range: 10m-980m

Maximum Range: 1,500m

Feed System: 60 round detachable magazine

No. Produced: 180 billion

The Colt M36 Rifle is the standard infantry weapon of UTF forces, including the UTF Army and UTF Marine Corps.

The M36 was designed by Colt Firearm designer Jonathan Stafford in the year 2210. The M36 relies on electrothermal-chemical ignition of cartridges in order to increase accuracy and muzzle velocity, and uses the powerful 6.8x31mm caseless cartridge to deliver powerful kinetic energy into its target.

The M36 is a select-fire weapon, and can be fired in semi-auto mode, 3 round burst mode, and full-auto mode. The weapon also comes with a large selection of high-tech scopes, which can help detect targets, provide aiming assistance, and gives the user information about how many rounds the weapon has left. As of 2259, the weapon is still in service.

Alright, here’s my question: Is my weapon realistic? Could you realistically get a caseless, ETC Rifle chambered in 6.8x31mm to work?

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – L.Dutch
    Apr 3 '21 at 17:44

A few issues

  1. Barrel length is very short, longer can easily be achieved by making it a bullpup (as was done in the H&K G11, the only (almost) production caseless weapon to date). This will reduce peak chamber pressure, which is always a good thing for weapon longevity.
  2. Effective range of 10-980m - regarding the short range, room clearing will generally occur at less than 10m except for big rooms. 980m is very long for "effective" range for a small round without terminal guidance, as atmospheric variables and resistance will knock it off course and slow it to ineffective speed regardless of how high the muzzle velocity is or how accurately it is fired. (Unless the 980m figure is for use in vacuum and refers to the limits on how steady the weapon can be held.) Add terminal guidance and rocket assist (ie smart bullets - which are a thing) in order to be effective a kilometre out.
  3. Rate of fire - As per a comment, it appears that these rates are switched around. 500 rpm is fine for standard full auto, otherwise just wasting ammo. The reason for the 2000 rpm for 3 round bursts for the G11 was to minimise the amount that the muzzle could climb between the first and third rounds so that a 3 round burst at (I think) 300m would all hit a man-sized target if aimed correctly. (Need to dig out my reference books to check my memory on this. Note that the 2000 rpm was for one burst, the effective rate of fire using 3 round bursts would basically be 3 x the rate of firing single shots. Firing a single shot from the G11 apparently felt the same as firing a single shot from a comparable rifle.) Your comments refer to the firer wearing an exoskeleton - if this acts like having the rifle fixed to a bench then possibly a lower rate of fire will allow 3 round bursts to all hit a person-sized target at the same range or the 1800 rpm will allow a 3 round burst to all hit the one target at longer range.
  4. Scope - I understand that either an open (holographic?) sight or two different scopes can be attached to the Picatinny rail on top of the weapon, but both scopes appear to have identical characteristics listed. 6x is probably inadequate for engaging targets at 980m. However, I would suggest that by this point there would be one day/night scope with highly variable magnification only, with magnification and crosshairs automatically adjusting based on the range to the target being viewed. Open sights would not be required if this is being used in exoskeleton armour with a helmet, simply project the point of aim onto the user's heads up display (HUC) if they are not using the scope. (Note that scopes like these have been around for a while already, I had a chance to briefly play with one over 20 years ago.)
  5. Trigger - there's nothing fundamentally wrong with having a trigger the same as firearms have today, but I would frankly be amazed to see them still being used in 200 years. Squeezing a trigger without moving point of aim is one of the key skills in shooting today, but given that nerve interfaces can be used for basic control of artificial limbs already, I would expect them to be standard for military weapons in 200 years. (Assuming that people are still wielding weapons directly rather than controlling drones that the weapons are mounted on or just delegating the whole business to the robot overlords.)
  6. Number produced - 180 billion! Either these are throwaway weapons with a new one issued each day or there's a massive number of highly populated planets with a large proportion of the population armed. It certainly puts the AK-47's production run to shame. The problem with this number of weapons is that if humanity has multiplied so far and so quickly, this is a very tame weapon compared to some of the possibilities being explored today. Examples include Metal Storm and it's pre-loaded barrels of ammunition (change barrels rather than changing magazines), various flechette projectiles etc.

Overall though, there is nothing fundamentally wrong with this design. Very similar to the weapons catalogue from the original edition of Traveller 2300 science fiction roleplaying game back in the 1980s, which was intended to be as "hard" sci-fi as possible except for the "stutterwarp" drive to allow FTL.

  • $\begingroup$ Several caseless forearms have been tried since the G11, just look at the textron $\endgroup$
    – John
    Apr 1 '21 at 5:12
  • $\begingroup$ Good point with the bullpup. The question would be if this "futuristic" look-and-feel is desired for the setting or not. $\endgroup$
    – o.m.
    Apr 1 '21 at 6:48
  • There is a difference between electrical firing of the primer and ETC propellants. Clarify in your text what you mean.
  • Not effective below 10m? I would have thought they put some effort into urban actions (or spaceship boarding). Do laser sights come as standards? Wired into the helmet visor?
  • The ETC round needs electrical power. Is the battery in each magazine or in the stock? What is the battery capacity?
  • Does it make sense to have a conventional-shaped magazine with 60-round capacity? Look at either a drum, or a longer, horizontal magazine on top like the H&K G11 or the FN P90.
  • With electric ignition, the cyclic rate should be easily adjustable. So why not a higher rate for three-round bursts and a lower rate for sustained fire? (See the G11 again.)
  • $\begingroup$ the G11 mag you are talking about is a 100 round, the 50 round mag was fairly short. Although you are right it should be a straight mag. $\endgroup$
    – John
    Apr 1 '21 at 5:11

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