Alien's M41 Puls Rifle design question

[taro8 806]

Hi, I just wanted to ask for a clarification from someone who knows a bit more about guns then I do. Recently I looked at an M41 Pulse Rifle from Alien franchise and I noticed that it has an ejector. Since the original prop was based on Thompson SMG and it was used to fire blanks I guess it was necessary. However it got me thinking: wouldnt a gun that use caseless ammo didnt need an ejector? After all if there is no casing that needs to be removed then why add more parts?

Of course Im talking about the inuniverse reasons rather then movie production stuff I mentioned above.

[BadHabitz 235]

Maybe it allows them to use various types of ammunition.

[roberthammer 582]

I think its there for same reason as arma 3's MX gun , so it can fire cased ammo too - also if the gun jams he can clear it quickly with the ejection port

[taro8 806]

also if the gun jams he can clear it quickly with the ejection port

Now that is a good point. Still, then why would the ejector port open with each round fired? Wouldnt it mean loss of propellant energy that escape and could be given to the projectile?

Damn, now I want to have a version of the pulse rifle that would support rails and replace all the wimpy sounding MX weapons. There is actually an Arma 3 mod that added M41. I think it would be pretty interesting as it would remove the need for separate machine gunner and grenadier, thanks to 95 round magazine and inbuilt grenade launcher. With PBO I would need to extract to edit NATO inventories?

Edited January 6, 2015 by Taro8

[krzychuzokecia 710]

if the gun jams he can clear it quickly with the ejection port

That, and unloading of course (though on the other hand one should unload weapon without magazine, so empty mag well acts like ejection port...)

Still, then why would the ejector port open with each round fired?

Probably because the cheapest/simplest way is to make the port "closed" by the bolt (so when the bolt moves back it opens the port).

Wouldnt it mean loss of propellant energy that escape and could be given to the projectile?

Any loss of propellant energy is caused by gases sent back to make the gun reload automaticaly - this is called "gas operated reloading". However many argue if such loss of energy is significant enough to have any effect on the ballistics of the bullet/projectile. This is an old academic discussion between precision shooters using bolt action rifles, and those who use gas operated (semi)automatics. Bolt action users say that automatic weapons are "less accurate" because not whole energy of propellant is transfered to projectile. However, those who use automatics say that loss of accuracy is actually caused by the effect of the gas systes it has on the barrel - the barrel can't be really free floated (like it is in bolt action rifle), and the weight of the gas system affects barrel movement after shot (harmonics).

What I wrote is very simplified and I can't even properly name that in English (it's not my native language), but I hope You'll understand at least some of it :)