Full auto weapons, and Rates of Fire.

[Blue Ghost]

I hate to bring up this topic in light of recent events, but this has been a topic that's always bothered me. Just let me get this out of the way first, Traveller is more than just playing with guns in space. A lot of the adventures I'm writing deal with real scientific challenges, and little "gun play". They are, in fact, revisiting some classic themes of challenging men's intellect and values with real decisions about options for best outcomes. I've brought up a lot of military and weapon related topics in Traveller, but Traveller was meant as a generic Sci-Fi game, and not just a shoot-em-up adventure game.

Be that as it may, I do have some serious questions about Rates of Fire. CT and MT rules state that a weapon spits out four rounds per trigger pull, or you can go into "panic fire" mode, and rattle off a magazine. This has always bothered me because weapons, contemporary weapons, fire great deal more than that, and I'm wondering how it might be possible to reconcile insane rates of fire into a Traveller combat scheme of things.

Forget the experimental stuff. Stick with what is doable. How might it be possible to import real world specs and performance into a Traveller rule set.

 

[mike wightman]

In the real world there is this thing called heat.

Fire a submachine gun or assault rifle for too long and its barrel actually glows red hot.

Hence the training to fire in controlled bursts.

The other reason for firing in bursts is accuracy, after the first few rounds you don't stand much chance of keeping a stream of bullets on target - firing the smg and AR that is.

 

[Blue Ghost]

I've only ever fired semi-auto weapons, so I'm a babe in the woods on this, yet I've seen Combat-Cam footage courtesy of the pentagon of guys firing off several bursts at a time.

I guess in "Hollywood firefights" things are a little different, but isn't there a chance of hitting with unguided rounds? I thought that was kind of the whole idea behind firing more bullets.

 

[mike wightman]

Putting more lead downrange is called suppressive fire - the idea is not so much to hit something but to make the bad guys duck so they can't return fire. The chance to hit with such suppressive fire is very small - all down to luck really.

It's why a lot of militaries use the buddy system - you move in pairs, one lays down fire while the other scuttles to the next bit of cover. Often this is conducted by fire teams of 4 - 2 move and 2 fire. It allows for casualties.

Scale it up and you have fire teams/squads firing while others manoeuvre.

 

[aramis]

Sustained fire rate for an M-16 is limited by several factors -
it's 5 sec or more to change mags, and it's 700Rd/Min ful auto rate for a maximum of 30 rounds. (Certain individual rifles can be up to 900Rd/Min, due to variations in model, lube and wear.) 2.5 sec to fire off the clip, then 5-15 to reload, for a prepared sustained fire of 120-180 rounds per minute through full basic load... of about 120-210 rounds.

If, perchance, someone keeps feeding you clips, after a couple minutes of this, you've got a barrel that will boil water. Anecdotals online indicate 5 clips on full auto is glowing red. That's 100-120 rounds, in under 60 sec.


An M60 can bend the barrel with several minutes sustained maximum rate, too. 1000 sustained rounds is sufficient to damage the barrel. Given the 500-600Rd/Min rate...
Given 1500-2000 rounds, you should expect droop. Yep, 2-5 minutes of solid fire can result in a bent barrel. Depends upon current quality of the barrel. Also note: 1000 rounds is 10 standard 100 round belts.
Also note: on aircraft mounts, heating was MUCH less an issue - the flow of air resulted in MUCH more rapid cooling.

The Vickers MG was water cooled for a reason... keeping the barrel from heat softening.

Note also: a barrel at droop temp might continue firing without issue - until you stop. The rounds and gasses themselves can prevent the droop. Once you stop in that range, however, it's toast city.

Also, the chamber and action can overheat, resulting in premature detonation and/or "runaway fire"... if the chamber is hot enough, the round in the chamber will go off. I've seen this happen once - with an 9mm autopistol. The exposed barrel cooled nicely - the chamber didn't. And we put a couple thousand rounds downrange that day.

At the low rates traveller combat offers, you're not likely to melt barrels outside of vacuum. (Vacuum results in a lack of conductive/convective cooling.)

 

[sabredog]

Be that as it may, I do have some serious questions about Rates of Fire. CT and MT rules state that a weapon spits out four rounds per trigger pull, or you can go into "panic fire" mode, and rattle off a magazine. This has always bothered me because weapons, contemporary weapons, fire great deal more than that, and I'm wondering how it might be possible to reconcile insane rates of fire into a Traveller combat scheme of things.

Forget the experimental stuff. Stick with what is doable. How might it be possible to import real world specs and performance into a Traveller rule set.

Along with the previously mentioned heat that can jam up your gun, and accuracy being effectively nil in a hand-held weapon fired on full auto (at range, anyway, but in a room with a lot of targets that'd be different) there is also ammunition capacity.

A modern automatic weapon will have an average of at least 500 rds/min. Even just an AK-47 fires 600. With a 30 round magazine that's about 3 seconds of full-auto firing time. Which also won't hit a lot of targets unless you are practically next to them and they are lined up right next to each other - but you will suppress the heck out of a lot of targets down range especially if they are not behind cover and/or inexperienced. So you'll go through a lot of ammo doing that and that's why on weapons like the M4 they use the burst fire mode. Which is pretty much the way Traveller has it work, too, with 3-4 rounds per pull of the trigger.

Now a belt-fed M60 or SAW is going to be able to lay down impressive and more accurate autofire, but even then it can only do it accurately if properly braced (not from the hip, but on it's bipod and the operator braced) and with a spare barrel handy for when it gets too hot or it will jam up and be useless for a while or worse. And its a heavy beast with a lot of heavy ammo.

Hollywood ignores all this (as do a lot of YouTubers who are not very experienced or knowledgeable even with what they are shooting) for dramatic effect, which is why in a movie autofire is insanely effective at ranges beyond 50 meters with spread out targets. And why you almost never see anyone change their magazines out until behind cover and delivering dialog. Exceptions are out there but they are few. But in a typical Hollywood gunfight with automatic weapons I've timed bursts between mag changes (if they even happen) with what appear to be magical "Mags of Holding" since they must have something like 200 rounds in that little 30 round magazine that lasts and lasts.

 

[hiro]

Most of what I present here was written offline, since when there have been several posts that I am basically repeating and hopefully adding to... I'm also thinking in Mongoose Traveller terms.

I think you'll find that very few current military doctrines teach that your average infantry man should use automatic fire. Automatic fire is as mentioned already for your support weapon (be it squad or platoon level) to be dishing out, in a suppressive and/or targeted manner. Most average joe combat load outs include 7 30 round magazines giving a potential 210 rounds it doesn't last if you shoot full auto and you'll be hitting precious little. Your platoon NCO will be caning your ass. And yes, barrels get real hot, real soon. Weapons designed for sustained automatic fire have quick change barrels.

When shooting semi auto you shoot your target till its no longer a threat, you don't stop at one hit, there's a good chance it will take more than one hit to put a person down. To interpret that in terms of ammo use I think it's best to abstract it, anywhere between one and six rounds (hah! conveniently a 1d6 roll!) is to me reasonable, depending on shooter proficiency and how long your target presented itself. Likewise the damage rules are abstracted, when you do 3d6 damage there's no hit location and it's up to the GM to suggest where the target was hit and how many times.

Not too long ago H&K had an experimental weapon firing caseless ammo (it's called the G11, see here: http://en.wikipedia.org/wiki/Heckler_&_Koch_G11) that had a breech unlike most current. It was said to be able to fire 3 rounds in a burst and the rounds would be so close together as to be considered one. I'm not sure what the reality was but suffice to say, with umpteen centuries to perfect it (the G11 has been dropped as far as I know tho am sure there are people out there trying to work out better ways of killing people) it seems reasonable that a Traveller era weapon could make similar use of automatic fire.

When looked at in a current context maybe full auto fire will have become a useable tool in the distant future for engaging a single target and will effectively add damage to a hit rather than just paint the wall behind your target with holes.

Suppressive fire is essential in a fire fight and I think the MGT auto rules do a fair job of simulating suppressive fire but you'd chew thru the rounds. The burst fire rules attempt to bring in the G11 idea where a burst of X rounds are fired very closely together tho I'd still go with the 1d6 bursts fired in one attack roll to give a number of rounds fired in total. From an ammo consumption/conservation point of view, it's just not what you'd do for each and every engagement.

sticking to whats doable and not experimental might be too close to ignoring that Traveller starts off in the far future - it all depends on how you want to take forward current technology and roll it into your TU

 

[aramis]

The G11 has a notable failure mode in overheat... detonation on feed, usually resulting in damage to the feed, but also possibly cooking off the entire magazine....

I understand that it's not ever actually cooked off a magazine, but has resulted in damage to the action... but that was due to mild overheat in 40°C....

 

[SanDragon]

At the low rates traveller combat offers, you're not likely to melt barrels outside of vacuum. (Vacuum results in a lack of conductive/convective cooling.)

Which begs the question:

Can CPRs be fired in vacuum?

 

[aramis]

Which begs the question:

Can CPRs be fired in vacuum?

Gunpowder is self-oxidizing (as are most explosives). The issue is one of lubrication, more than the ammunition. If lubed with the correct lube, yes. If not, for a few rounds.

Note that Gas-Op may have additional issues, due to pressure-based calibration (and the much more rapid drop once the barrel is open to space post-round).

 

[SanDragon]

Finally, a no-nonsense and logical answer.

Thank you.

 

[Enoki]

In realistic terms, fully automatic fire is generally a waste. The gun is inaccurate at anything more than very close range.

Then there is the ammuntion problem. Realistically a person can only carry 100 to 200 rounds (combination of bulk and weight) already made up in magazines. Maybe a bit more if you trade off other equipment.... Anyway, an automatic weapon goes through that pretty fast. Of course, part of that is the size and weight of the rounds. (One reason I like the Ruger 10/22 for a home defense rifle (big clips, light weight, lots of ammo, won't go through the neighbor's house but will stop you dead, go through a car, and is accurate when rapidly fired.)

Even with just game specified (and the character would have to be trained to do this in any case) four round bursts and 5 or so second rounds of combat you could burn off 100 rounds in a minute or so of fire. If that's all you have on you.... Opps!....

Jams are more common with many automatic weapons too, particularly when they get hot.

Another thing many less skilled individuals don't recognize or do is count rounds fired or automatically change clips. That is, they fire until the gun quits firing and then in mild surprise try to change clips at that point. More skilled shooters in such situations know how to combat load and also know enough to reload every chance they get with fresh clips saving the half full ones where possible.
So, it is not only possible but likely a person with say a submachinegun who has only basic skills with it (level 0 or 1 say) could find themselves in a combat round with just two rounds left in the clip after firing for several rounds short bursts and not paying attention to ammunition use.

So, in the current round they really don't have an automatic weapon. They get their one or two shots off and have an empty gun! That could be really bad if they had just decided to charge the baddies position....!

 

[sabredog]

Gunpowder is self-oxidizing (as are most explosives). The issue is one of lubrication, more than the ammunition. If lubed with the correct lube, yes. If not, for a few rounds.

Note that Gas-Op may have additional issues, due to pressure-based calibration (and the much more rapid drop once the barrel is open to space post-round).

Piston-driven gas-op would work more reliably. And some companies already make adjustable piston AR platforms like Ruger's SR-556 that might be pretty good for firing in vacuum.

Heat, as always would be a problem. It builds more rapidly in gas-piston systems than open ....and autofire weapons that fire from open bolts are more reliable than closed-bolt systems from a heat perspective.

 

[aramis]

....and autofire weapons that fire from open bolts are more reliable than closed-bolt systems from a heat perspective.

If nothing else, because chamber heat has less time in contact with the round to propagate through the casing to the explosive.

 

[Enoki]

Another likely vacuum problem is that the weapon will likely heat up faster as there is no conduction of heat just radiation of it off the various surfaces that have relatively small areas. That is, there is no air around the gun barrel and chamber to conduct heat away.

Another minor but present problem is smoke. As you fire, smoke from the burnt powder will build up around the weapon as there is no atmosphere to disperse it into. It wouldn't be as bad as black powder but "smokeless" powder still gives off some smoke when combusted.

 

[sabredog]

Well, presumably...and this has been pointed out in other threads...since we are talking about a space-going civilization these issues have been addressed and solutions developed. So heat dispersal and retention might be addressed by purpose-built designs and materials technology.

And there is always the problem of recoil in zero-G: which will be when the majority of Uzi-in-a-vacuum incidents will occur. The problems inherent in that with a character who might not have the Zero-G Combat skill are bad enough without bringing in all the other issues. Just imagine ripping off a full magazine load of even more powerful ammo while floating in space, or even while one hand is on a grab rail in a corridor.

 

[mike wightman]

Another likely vacuum problem is that the weapon will likely heat up faster as there is no conduction of heat just radiation of it off the various surfaces that have relatively small areas. That is, there is no air around the gun barrel and chamber to conduct heat away.

One of the things the brass case on a round does it take waste heat away with it - this was one of the issues caseless rounds couldn't cope with.

Another minor but present problem is smoke. As you fire, smoke from the burnt powder will build up around the weapon as there is no atmosphere to disperse it into. It wouldn't be as bad as black powder but "smokeless" powder still gives off some smoke when combusted.

Nope. Just nope. You are firing in a vacuum remember?

What happens to smoke/gas in a vacuum - it spreads out really quickly.

 

[BlackBat242]

The Vietnam-era M-16A1 had single and full-auto settings.

About 1980 the M-16A2 began entering service.
This had no full-auto setting... it had single and burst settings.
Burst fires 3 rounds per pull of the trigger.

 

[aramis]

Nope. Just nope. You are firing in a vacuum remember?

What happens to smoke/gas in a vacuum - it spreads out really quickly.

Misconception notice to BOTH of you.

What comes out of the barrel is a mixture of gas, ash/particulates, and unburned-but-still-burning powder granules.

The gas will pretty much immediately spread to invisibility.

The particulates, both ash and unburned-but-still-burning powder granules, are moving several hundred meters per second, and won't slow down until gravity makes them hit a surface (unless fired upwards). (In atmosphere, the particles slow down much faster than bullets due to much lower mass:drag ratios than bullets.)

It's worth noting that the unburned-but-still-burning powder granules will produce a bit of a glowing trail, and won't flare as they do in atmosphere - powder burns will occur at longer distances as atmospheric oxygen won't allow for faster burning, but the combustion will be potentially even less intense, since, again, no atmospheric oxygen is being added.

As anyone who has shot at close quarters can tell you, damage to stuff around you comes from both hot ash and burning powder embers, and if close enough, from the hot gas.

Another interesting thing is that modern gunpowder (nitrocellulose/nitroglycerine mixture) combustion produces still-flammable chemicals - part of muzzle flash is these volatiles being exposed to atmospheric oxygen. Namely, molecular hydrogen (H2) and Carbon monoxide (CO). The lack of air means this secondary combustion can't occur; muzzle flash will be reduced in intensity for lack of combustion. It will be further reduced for the longer travel due to lack of air-resistance.

http://www.democraticunderground.co...mesg&forum=118&topic_id=156466&mesg_id=156517

 

[SanDragon]

Which leads me to believe that you better switch to an ETC or low-recoil energy weapons in vacuum...