Wanted: CT/MT Stats for Mac SMG

[kaladorn]

Originally posted by Corejob:
M855 ball ammunition (5.56x45mm) masses 12g. The HL G11 4.7mm caseless cartridge masses 7g. It should be noted that the M855 has a 4 bullet at 921 m/s for about 1670J vs the 4.7mm with a 3.4g bullet at 930 m/s for a muzzle energy of 1460J.

The caseless round does show a significant weight savings, although anyone who worried that the 5.56 is too small will find the G11's round microscopic.

True enough. But I don't recall making particular reference to that sort of comparison. I'm thinking a 7mm cased round vs. a 7mm caseless round or a 5.5mm cased round vs. a 5.5mm caseless round, assuming the same energy output/muzzle velocity/bullet mass.

I had a chance to handle the ACR version of the G11. Human engineering is certainly not HK better areas. The weapon feels like a 9 lbs 2x4. It's big and clunky.As a first iteration, it wasn't bad I suppose.

If that's bad, what would you call the current OICW iteration? What was the weight on that empty? And with ammo loadout standard? OUCH!

My understanding is that obturation is still a problem. The weapon vents propellant gases into the interior. Still, it is probably no worse than the M-16. Despite the venting, the weapon apears to continue functioning.

Who knows what more efficient powders might be developed that liberate less heat energy and more 'boom'? Or what materials and microcooling technologies may wick this heat away rather trivially? Basically, if a TL-8 version works, a TL-10 version should be fantastic.

I agree that assuming all the problem with caseless ammo are worked out, it does make sense if you are already planning on replacing your rifle. You are however, limited to certain projectile types that lend them selves to encapsulation. At the very least, flechettes don't appear to be an option with the HK design.

Though perhaps less limited than today's situation.

As to flechettes, could flechettes inside a discarding carrier not work?

I should still have some photos of the various ACRs, including the G11. I'll ook for them and post them on one of my web sites. My personal favorite in terms of ergonomics was the Steyr ACR.

Well, I hope it is a different beast to the AUG. When comparing the C7 and the AUG, the AUG came off really far behind, in terms of how much it seemed to weigh, its ergonomics, and its 'comfortability of use' (I can't really put it much more clearly... it just didn't feel as good).
Of course, the SA80 had absolutely abysmal optical sights.... it did terribly in conditions that were partly cloudy, partly sunny....

More data on the G11 is available at http://www.hkpro.com/g11.htm including comparisons with other weapons.

Was there just recently

 

[Uncle Bob]

AFAIK obturation on the G11 is achieved with a precise sliding metal-to-metal fit. Same as the blackpower Cookson, Ferguson, and Sharps rifles.

As an alternative to caseless consider polymer (or brass/polymer composite) cases. The Steyr ACR used a polymer case that reportedly had problems with erratic chamber pressure. The US Army is currently developing a composite case for the M16. My best guess is that M855 equivilent will weigh about 8 g.

 

[Todg]

Originally posted by Uncle Bob:
AFAIK obturation on the G11 is achieved with a precise sliding metal-to-metal fit. Same as the blackpower Cookson, Ferguson, and Sharps rifles.

Yes. There's a raised extension on the chamber (which is disk shaped) that engages the barrel on one side, and the firing pin/obturator on the other. These two areas only fit tightly with the rest of the chamber area when the round is 'in battery' to reduce wear, otherwise they spin freely. It's pretty clever.

But just like the apexes on a wankel engine, these point do eventually wear. Fortunately, it's a rather trivial repair. I don't know how long between changes, but I suspect that with carefulk design and good metallurgy it could be many thousands of round. The weapon I looked at was one of the ACr test guns and had undergone a lot of firing. I'll post off an email to my HK contact and see if he knows what the lifetime is.

As an alternative to caseless consider polymer (or brass/polymer composite) cases. The Steyr ACR used a polymer case that reportedly had problems with erratic chamber pressure.

When you consider that the AAI SPIW needed a chamber pressure in excess of 70,000psi to get a flechett up to 1500 m/s (the muzzle velocity of the Seyr ACR) that's pretty scary.

The US Army is currently developing a composite case for the M16. My best guess is that M855 equivilent will weigh about 8 g.

I've heard this as well. Any good sources? So far, I can't track this rumor down to a contractor or project.

As for caseless alternatives, there are a whole series of possible solutions. Consider the old 'chicklet' rounds. They were cased in plastic, but when fired, the case softened and was blown down the barrel after the projectile. That was 1960s technology, we should be able to do better today.

Or, to go back to one of Kaladorn's examples, the bullet and propellant could be entirely separate. The bullet gets inserted into the firing chamber, and then a liquid or gas is injected afterwards and fired electronically. Seems complicated for a rifle, but in Traveller why not?

Imagine the following: a liquid filled gun where one can adjust the propellant charge on a per round basis. Just turn a know to up the velocity. turn it the other way to reduce penetration or recoil. Seems kind of silly, but why not? This is SciFi after all.

For that matter, the liquid could be inert material like water. A potion of the water is converted to plasma via electric current and stimulated the rest of the working fluid.

Its not a far step to ET guns once you have the battery technology. Hughes or Lockheed (can't remember which) deonstrated a CAP (combustion augmented plasma) ET powered M-16 in the 1980s that had double the muzzle velocity of the standard rifle with exactly the same peak chamber pressure.

Naturally, we have wandered way off topic. Maybe it's time to start a different thread. But there is certainly lots of stuff to be mined here.

 

[kaladorn]

I think Electrothermal Combustion (ETC) is one possibility indeed of interest in a sci-fi setting.

And the whole BP (Binary Propellant) thing figured heavily in 2300. Their weapons did adjust the RoF and presumably muzzle velocity when in autoburst to make bursts more controllable. And the binary propellant would be (for things like tanks, howitzers, etc) better if the individual unary components of the binary were themselves non-volatile (ie only volatile as a binary). This cuts down risks associated with carrying volatile ammo.

There are a lot of neat things to have in Trav. I like the idea of BP because if you find your nice controllable bursts that were working so well against the indigs even though the rounds were moving a bit slower (they have no armour) start failing up against some newly arrive power armour, you crank up the BP and go back to single shot high power to crack the armour.

Lots of neat sci-fi goodness here....

And I would be interested to see (re: G-11) the lifespan of the rotating breech affair (how often does it need parts replaced? Is this a field strip task or a detail strip or send to weapons shop for a week with the tech?). So please post if you get some info.

The one thing about all this variety is it offers lots of neatness for Traveller games. And the Imperium is big, so that's a good thing.

 

[Uncle Bob]

Design, Analysis and Testing of a 5.56mm Polymer Cartridge Case

 

[Straybow]

kaladorn, I'm one who believes in loading my own magazines. I grant you that you may not normally carry much loose ammo, but when you do it saves the weight of a dozen magazines.

Sounds to me like a trade-off between caseless rounds that come from supplier in magazines, or supplier rounds in cases that I load into a few magazines myself.

 

[Uncle Bob]

A 30rd mag of 5.56mm M855 weighs 0.5 Kg, of that
0.1 Kg is magazine, 0.2 Kg is brass cartrige case. And that is a heavy GI magazine.

 

[kaladorn]

So, if you can dispense with 40% of the mass, that's significant.

And self-loading mags isn't bad. Our rifle team used to do that... never loaded more than 28 rounds to prevent feed issues. OTOH, combat operates on a different timescale. There are plenty of times in the field that I actually got someone to chuck me a mag during an excercise... loading loose rounds just wouldn't have made sense. And linking ammo for MGs is just a plain painful activity....

Anyway, there is a place for cased rounds.

So far from this discussion, we've realized the following as sci-fi-ish items:

Metalstorm GLs
Flechette firing ACRs
ETC or BP guns
Caseless ammo
Polycarbonate or other synthetic casings

That's pretty good, for one short thread.

Now, to turn some of this into game items and game stats.

 

[Todg]

Originally posted by kaladorn:
So, if you can dispense with 40% of the mass, that's significant.

And self-loading mags isn't bad. Our rifle team used to do that... never loaded more than 28 rounds to prevent feed issues. OTOH, combat operates on a different timescale. There are plenty of times in the field that I actually got someone to chuck me a mag during an excercise... loading loose rounds just wouldn't have made sense. And linking ammo for MGs is just a plain painful activity....

IMTU, by TL 8 most magazines are preloaded and disposable (military anyway). You can buy olod style reloadable mags and load them yourself, but they are more expensive.

And naturally, caselesss rounds are replacing cased ones.

Hope I'm not being too verbose or technical. My usual haunt is the Infantry forum at http://www.infantry.army.mil but it's been down for a while.

 

[kaladorn]

For the record, we reloaded disposable mags in the early days, until more robust ones were available. Remember, we (me and my unit mates) were/are in NATO's cheapest (or right down at the bottom) military spending nation by % of GDP (GRRR!).

I enjoy the technical conversations. I find it is these details that make your presentation of new gizmos in the game more 'real' and gives a verisimilitude to them.

If you have players like mine, who ask questions and chew on things, and spit back unreasonable, poorly thought out or unlikely ideas, then having this done ahead of time solves many problems before they ever occur.

 

[Todg]

Originally posted by kaladorn:
If you have players like mine, who ask questions and chew on things, and spit back unreasonable, poorly thought out or unlikely ideas, then having this done ahead of time solves many problems before they ever occur.

I have players that a RL gun experts, some prior service, others just extremely well informed amateurs. I've also had most of my players for 20 years.

New players, ones not so cynical, experienced and twsity clever, would be fun. After a while, you tend to use up all you ideas. I am definitely there. I need to be a player for a while, just to see what it's like. I've forgotten.

BTW, and not that most people care, we post our gamenotes on the website. I have a scribe who's really quite good about turning them into a decent narrative and linking all the crucial details. Follow the links at http://www.travellercentral.com for 'Planet X' Regina or "Solomani Rim'

 

[kaladorn]

Being a player is a great treat. If you're an ex-ref, you also bring some insights to the table (hopefully without too much 'I'd do it this way' baggage). It does remind you what it is like to be on the other side of the table.

I'd link you to my website, but I'm concerned about IP issues - I've go a lot of stuff that is variant MT rules and that just can't be advertised. To be legal, I have to restrict it to my group, and sorting out the 'publishable' from not is just a bit hard.

My players, my AD&D guys for 16 years, are several active service people (Navy and Army), a couple of military historians (one with a Master's in War Studies from RMC), some programmers, some electrical engineers, a computer tech, a race car guy, a bunch of shooters, a construction engineer/lighting guy, some theatre types, a cop, a space weapons/satellite guy, and the like (some of those are stated twice since they hit different areas.. the group numbers around 7 or 8).

The nice thing about familiar faces is they know what they're getting and are accustomed to it. Some things are quite smooth as a result. The downside is you have to watch it doesn't get stale.

 

[Rupert Boleyn]

Originally posted by Corejob:

And most militaries have abandoned the SMG except for very specialized work. Compact assault rifles are almost as small and have superior armor penetration and killing power. The SMG is old technology and seems destined to the same fate as the bolt action rifle. Reserved for very special applications.

Aside from the SAS I'd be moderately surpirsed if the NZ armed forces have any SMGs outside of some old Sterlings in the back of Air Force and Navy armouries, lying there forgotten. Aside from some that MP officers and SNCOs have the nearly same goes for pistols. The current view is that for the same weaight and bulk as a pistol you can carry an extra 30-round magazine or two for your rifle. That's a lot more extra fire-power than the pistol will give you.

 

[Rupert Boleyn]

Originally posted by Corejob:

Originally posted by far-trader:

3 extremely fragile - in the sense of fouling and more importantly when it came to hand to hand one good hit and you'd probably break the buttstock and just annoy the enemy you hit while the same hit from the much heavier AK would hurt a lot more and do no lasting damage to it

This may have been true once, The latest generation of stocks are made from an extremely durable polymer.

I don't think it's ever been true. Back in the late 80s we had M16A1s, most with the original fibre-glass furniture, and the only ones that got broken suffered things like having trucks drive over them. Also, I've seen footage of Phillipine soliders dealing with captives with their (M16A1) rifle butts. Not one rifle broke, but the captives were certainly worse for the wear.

And to the OP - the Ak-47 isn't "much heavier" than an M16A1 (and the M16A2 is heavier than the A1). An Ak-47 is a pound or two heavier than an M16, and an Akm-47 with its folding stock weighs the same as an M16A1, possibly a little less.

 

[Rupert Boleyn]

Originally posted by Uncle Bob:

If the XM8 is adopted soon, it will be in the "auto rifle" version to replace the M249s in rifle squads. The USMC has expressed a need for a weapon shorter and lighter than the M249, preferably more accurate with a box or drum feed instead of a belt. I suspect the Army will eventually follow.

I don't know what the US did to the FN MINIMI design when they made the M249, but it can't have been good. We use the Canadian license version of the MINIMI (the C9), and it's a nice, light, reliable, and accurate weapon IME.

 

[Uncle Bob]

Empty weight, from http://world.guns.ru/main-e.htm

AK-47 4.3 Kg
M16A2 3.77 Kg
AKM 3.14 Kg
M16A1 2.89 Kg

 

[Uncle Bob]

We loved the Minimi fifteen years ago, we loved it in Desert Storm.

But now they are all at least ten years old and loosened up from firing hundreds of thousands of rounds. They need to be rebuilt or replaced, and rebuilding costs as muchh as replacing.

 

[Rupert Boleyn]

Originally posted by Uncle Bob:
Empty weight, from http://world.guns.ru/main-e.htm

AK-47 4.3 Kg
M16A2 3.77 Kg
AKM 3.14 Kg
M16A1 2.89 Kg

That M16A1 weight is wierd. We were told in Basic that an M16A1 loaded with a 20-round magazine weighed 3.65kg. Now there's just no way a disposable 20-round M16 magazine weighs 0.76kg.

 

[Rupert Boleyn]

Originally posted by Uncle Bob:
We loved the Minimi fifteen years ago, we loved it in Desert Storm.

But now they are all at least ten years old and loosened up from firing hundreds of thousands of rounds. They need to be rebuilt or replaced, and rebuilding costs as muchh as replacing.

IOW the problem isn't actually that the M249 is inaccurate or unrealiable, it's that nobody bothered to sort out how to keep them in good condition, either through a rolling rebuild program, through budgetting replacements, or by buying way more than were needed in service so as to provide a stock of new replacements.

 

[Todg]

Personally, comnsidering how infrequently the magazine feed is used, I think we would have been far better off with the CETME Ameli MG

http://world.guns.ru/machine/mg25-e.htm

Got to fire one of these back in the mid 80s. Absolutely reliable, light and one hell of a buzz gun (1200 round per minute). Of course, the M-249 is more complicated, therefore more likely to appeal to the American military. Besides, who ever heard of a superior gun coming from Spain?