25mm Grenade Launchers

[vicky_molokh]

Originally Posted by Fred Brackin

Also note that UT battlesuits have Protected Vision and Hearing. This definitely stops the extra effects of explosions from HT and Tactical Shooting. It should probably reduce any other psychological effects.

Serious battlesuit training probaly live fires ineffective grenade rounds at the trainees. A battlesuit is _supposed_ to make you immune to the effects of light weapons such as HE grenades. Actally it's probably supposed to protect from relativley heavy weapons like IEDs.

Not being blinded and deafened by the flash, wave and and fragments is certainly nice, but I don't see how they will help against psychological effects. The battlesuit trooper still knows something suddenly makes a big boom. And it is not easily discernible in the fraction of a second when it happens whether this is a 25mm, a 40mm, an artillery shell, and what type of warhead beyond 'explosive'. It's still a potential deadly threat. You just don't know for sure. It's kinda like hiding behind a DR7 metal table when the enemy fires 1d+2 bullets - it might make you immune, or not.

Now, Enhanced Time Sense may help know some of those things in time . . .

[The Colonel]

Originally Posted by Anaximander

This is not the role I envisioned for GLs in my game. I rather figured that the GL would be used to frag the big, tough targets. Is there something I am missing in the stats of the weapon and how it does damage? How can I improve this without handing out shaped charge warheads and rpgs?

You can't. Grenade launchers engage armoured targets with HEAT/HEDP/HEMP - if at all. They're mostly a replacement for the light mortars people used in the (roughly) middle third of the 20th century (or back 2/3rds if you happen to be from the UK...) - ranged anti-personnel HE, not an anti-armour weapon.

[panton41]

Originally Posted by Anaximander

My players picked up a 25mm Grenade Launcher, whose stats I based off of the under-barrel grenade launcher listed in GURPS Ultra-Tech. Loaded with HE rounds, they are practically useless at damaging armored opponents; which are relatively frequent in my game.

They seem to be able to pin the enemy down. The explosion itself causes some knockback and conceivably forces some will checks, but only on a direct hit. The fragmentation damage also does nothing to an armored target and there's really no point in indirect fire except to make noise and maybe collateral damage.

For sealed, hardened UT armor that's probably pretty realistic. Against TL8 body armor, remember that limbs are poorly protected and there's concussive effects.

This is not the role I envisioned for GLs in my game. I rather figured that the GL would be used to frag the big, tough targets. Is there something I am missing in the stats of the weapon and how it does damage? How can I improve this without handing out shaped charge warheads and rpgs?

A 25mm HE grenade is about the size of a large man's thumb and a large percentage of it's mass is metal. You're probably looking at an actual warhead that's a sphere or egg about 23mm in diameter (assuming they're anything like a 40mm grenade internally). The explosive force in a bomb that size is pretty small and the fragments are the real killing force. Hand grenades (and even large multi-hundred pound aerial bombs versus some kinds targets) do most of their damage through fragments and are more likely to wound than kill. (Unless we're talking those large aerial bombs, their fragments will tear a man in half.)

[Ulzgoroth]

Originally Posted by Anaximander

My players picked up a 25mm Grenade Launcher, whose stats I based off of the under-barrel grenade launcher listed in GURPS Ultra-Tech. Loaded with HE rounds, they are practically useless at damaging armored opponents; which are relatively frequent in my game.

They seem to be able to pin the enemy down. The explosion itself causes some knockback and conceivably forces some will checks, but only on a direct hit. The fragmentation damage also does nothing to an armored target and there's really no point in indirect fire except to make noise and maybe collateral damage.

25mm grenade launchers are a bit dubious to begin with, and totally inappropriate to lobbing HE at well-armored targets. They're really small payloads. Pass the HEAT or more exotic payloads, unless you're shooting at unprotected infantry.

25mm GL might be somewhat high velocity, I don't recall. What would you get if you loaded it with APEX? Not indirect fire, but could make a bit of an elephant gun out of it.

Originally Posted by Anaximander

This is not the role I envisioned for GLs in my game. I rather figured that the GL would be used to frag the big, tough targets. Is there something I am missing in the stats of the weapon and how it does damage? How can I improve this without handing out shaped charge warheads and rpgs?

HE is fundamentally a bad way of attacking big, tough targets. In many video games it can work because 'tough' means 'lots of HP', but GURPS doesn't work like that. When hard targets are killed with HE, it's based on using seriously gratuitous amounts of explosive. 500 pound bombs or IEDs, not warheads for man-portable weapons.

If you really want to use concussive attacks against armor, contrary to effective practice, a 40mm launcher with thermobaric warheads is at least a step in the right direction. IIRC that will defeat some weaker armor. 64mm thermobarics are actually a threat to power armor.

Originally Posted by vicky_molokh

Not being blinded and deafened by the flash, wave and and fragments is certainly nice, but I don't see how they will help against psychological effects. The battlesuit trooper still knows something suddenly makes a big boom. And it is not easily discernible in the fraction of a second when it happens whether this is a 25mm, a 40mm, an artillery shell, and what type of warhead beyond 'explosive'. It's still a potential deadly threat. You just don't know for sure. It's kinda like hiding behind a DR7 metal table when the enemy fires 1d+2 bullets - it might make you immune, or not.

You're going to have a completely different physical experience from people not so protected. All that armor means that your senses and general physiology aren't traumatized. It also means that your body isn't crushed, burned, or shredded, which you're probably aware of.

[Joseph Paul]

One thing you could do is stat up a 25mm ramjet round. A thin outer shell carries a propellant molded around a penetrator with an airspace for combustion. It is fired at a a high enough velocity to sustain ramjet combustion and continues to accelerate until burn out. Good only in atmospheres with enough O2 to support combustion. Do the math or make a judgment call on damage. You should be able to get an armor divisor out of it.

[Kromm]

Originally Posted by Ulzgoroth

HE is fundamentally a bad way of attacking big, tough targets. In many video games it can work because 'tough' means 'lots of HP', but GURPS doesn't work like that.

This sums it up best.

—

First, real-world weapons of this kind are optimized for attacking many soft and typically concealed targets over a small area, and not for striking a single hard target dead-on. A grenade launcher is basically a low-powered, big-bore shotgun capable of lobbing small gobs of explosive a lot farther than you could throw them. It isn't a proper anti-armor weapon! A 25mm or 40mm weapon powerful enough to defeat armor kinetically would smash the person firing it. A man-portable weapon powerful enough to defeat armor explosively would need to be larger than 25mm or 40mm; that's why RPGs have 80-150mm over-caliber warheads.

Second, video games ignore all this in favor of the Rule of Cool: Of course you use the biggest-bore gun that you have against the toughest bad guy! Of course a projectile that goes BOOM is better for this than one that doesn't! Video games also regularly conflate grenade lauchers with rocket launchers (which are good for fighting hard targets), up to and including in the character dialog. Video games and action movies make crappy reference points for real-world armaments.

Realistic options are to make the mooks soft targets, so that a single fragment or a few HP of concussion will demoralize or incapacitate them, or to issue a weapon built to fight hard targets. The latter is realistically a recoilless or rocket-propelled projectile launcher, although some fancy grenade-launcher rounds might suffice, if barely.

Cinematic options are to make "hard" mooks softer by swapping out DR for HP, or to issue some sort of science-fictional ammo that can reliably defeat DR from a low-powered 25mm barrel. Just going to high-velocity 25mm cannon rounds and ignoring recoil would be a start.

[Kraydak]

One thing is that, if UT explosives are useless against common armor, then the militaries will tweak them to become useful, or not issue them at all. It would be nice to have rules for increasing the number of fragments (at the expense of fragment damage, to increase the chance of getting a hit on an un/underarmored location) or increasing fragment damage (at the expense of fragment number).

[Kromm]

The bad assumption is "common armor." Armor has existed for as long as there has been warfare. It has always been the preserve of the wealthy individual (knight, samurai, whatever) or the rich nation. For everybody else, there's prayer and fate. This hasn't changed from TL1 to TL8, and I doubt that TL9+ will change this unless you posit a post-scarcity world for all, in which case why are people fighting wars? So in a TL9+ world with warfare, most targets will remain ill-equipped, unarmored conscripts, ill-equipped, unarmored guerrillas, and ill-equipped, unarmored Third World professionals. That's why HE won't go out of style in infantry weapons. When the rich kids fight each other, though, they'll have armor, and thus use armor-piercing weapons rather than peasant-killer weapons . . . just like knights did.

[vicky_molokh]

Originally Posted by Kromm

The bad assumption is "common armor." Armor has existed for as long as there has been warfare. It has always been the preserve of the wealthy individual (knight, samurai, whatever) or the rich nation. For everybody else, there's prayer and fate. This hasn't changed from TL1 to TL8, and I doubt that TL9+ will change this unless you posit a post-scarcity world for all, in which case why are people fighting wars? So in a TL9+ world with warfare, most targets will remain ill-equipped, unarmored conscripts, ill-equipped, unarmored guerrillas, and ill-equipped, unarmored Third World professionals. That's why HE won't go out of style in infantry weapons. When the rich kids fight each other, though, they'll have armor, and thus use armor-piercing weapons rather than peasant-killer weapons . . . just like knights did.

According to UT, Typical Armor by TL:

Originally Posted by UT186

TL9
Civilian and Police: Reflex jacket, trousers, vest or
tailored armor. For spacers, a civilian vacc suit or zero-G worksuit.
Light Infantry or Paramilitary: Reflex tactical suit {DR 20/10, flexible} or
vest; light infantry helmet { DR 18 }.
Mechanized Infantry or SWAT: Combat hardsuit {DR 50/30, hard, sealed} (or
space armor), or powered combat armor.
Heavy Powered Infantry: Combat walker {duh}.

Braces include added DR for convenience.
The Reflex Tacsuit, which is the typical (i.e. neither the élite nor junk, I assume) armour of paramilitary and light infantry units, provides DR10 against Crushing damage, stopping 3 out of 4 dice that grenades do. That's for the same-hex hit, though admittedly not counting any peculiarities of different armour levels across the body. That's with light infantry and paramilitary types. Even with SWAT-level armour, we get enough DR to survive (but of course not ignore) a direct hit. And Heavies, indeed, are to be fought exclusively with AP weapons like Shaped Charges.

[RogerBW]

Since killer robots are pretty much the canonical examples of targets with lots of DR, Will to Live (obPlug: buy a copy! Buy several!) has a reasonably extensive section on weapon selection for when you're going up against them. To summarize: damage type and armor divisor matter more than base damage. In an Ultra-Tech game, shaped charge and SEFOP are best, APDS and APEP come next. And yes, you can fire shaped charge out of a grenade launcher... it just means you have to get rather closer to the robot than you might want to.