OK. I know about the Colt Water Carbine, The Gyrojet Pistol, and the Spear Gun, but what other weapons are useful underwater in the SR universe? Could normal weapons be modified to fire underwater?

I know that explosive weapons are particularily effective due to the hydrostatic force effect but what explosive weapons could be usefully deployed underwater?

What prevents a normal bullet from being used underwater? I don't believe that the explosive reacts with air - I suspect there isn't enough air in the chamber.

So, if you put a condom over a rifle barrel - would you be able to fire at least one bullet (before the water came down the barrel)? If yes, you should be able to get your first burst out, and long as you don't stop firing.

The SR guns are caseless, meaning there is probably no injection mechanism, right?

- personally, I prefer psychically-controlled sharks. But that's just me.

Fireing guns underwater causes alot of resistance to the bullet, so they will only be effective for very short ranges before they lose enough power and simply sink. As a GM, I would rule that a conventional surface weapon would only have roughly 1% of it's original range. I have seen it done in movies where AK-47's and various semi automatic pistols were fired underwater (all at point blank range). I don't know if it is realistic though. Maybe, maybe not. Perhaps Raygun can contribute his expertise.

Raygun! Raygun! Raygun!

...

Perhaps he's on the metaplane of reality right now...

As Buzzed stated, bullets lose a lot of stability underwater. An AK-74 has a "lethal" range of 1 meter underwater. The gyroscopic action that helps keep a bullet stable in air causes havoc on the trajectory underwater.

Underwater rifles usually use very long bullets that are (unfortunately) naturally unstable in air and use unrifled barrels to boot. There is, however, a relatively new rifle that fires two separate cartridges (selectable clip); one for underwater use and one for above water (ASM-DT)

Checking up on the ASM-DT, I noticed another thing which might give some info on the question of firing a normal gun underwater. This article sites the dangers of "possible barrel bulge, blowout of the cartridge case primer or deformation of the locking assembly". It also has some pics of the ASM-DT.

firearms work underwater, but they're more likely to jam--i believe that's caused by the resistance of water on the bolt. regardless, bullets face no obstacle in being fired underwater, though their range and damage will be reduced. bullets don't require an external oxygen supply; powder has oxygen 'built in', because it burns too fast to make use of oxygen in the air.

Well, learn something new every day.

An ink grenade might be useful.

Just leave the shock gloves at home....

When in doubt, just fart ....

Lasers? Just make sure you use a wavelength that water doesn't readily absorb.

Bubble, bubble, toil and trouble ....

Pretty much covered here. Like a few people have mentioned, gunpowder contains its own source of combustable gases (the nitro part in nitrocellulose and nitroglycerin, which also contain hydrogen and oxygen). Yes, you can fire a bullet underwater. Yes, you can fire a bullet in space. Water won't cause any problems after the cartridge has been ignited as the pressure created by the expanding propellant gases is much greater than the water around you. The bullet is well downrange before that pressure disperses. The next cartridge is self-contained, so no water ever touches any propellant. Even caseless firearms could be made to fire underwater quite easily as the caseless cartridges are just as impervious to water as cased cartridges.

Firing underwater will, however, pretty severely mess with exterior ballistic preformance because, as Buzzed and Game2BHappy said, water creates more resistance than the bullet, which is designed to travel through air, must overcome in order to "fly." The bullet will start to tumble because of this resistance (thus losing energy and destroying accuracy) almost as soon as it exits the barrel. Therefore, bullets designed especially for use under water must be used if the firearm is expected to be more than marginally useful. The ASM-DT is about as good as it gets right now.

Also, expanding type bullets (hollowpoints) can't be used as the hydraulic action of the water will cause the bullet to expand as soon as it contacts the water (read: in the barrel). That causes more friction, which in turn causes more pressure, which is then perceived as more recoil if you're lucky. The gun destroys itself (and maybe you too) if you're not.

Also, as mfb mentioned, many automatic firearms won't function correctly under water because of the increase in resistance. Bolts won't recoil at the velocity they're designed to, firing pins won't move the way they were supposed to, etc... Reliability takes a severe nose dive.

So in short, firearms have to be specially designed in order to present some practical benefit underwater. The environments are just too different for a weapon to function optimally in both.

Here's a link to HK's P11 Underwater Pistol.

how well does a pistol like that perform out of the water?

ah, cool. stupid army firewall won't let me on hk's site.

The Air Force firewall here on base blocks that site as well. Eh, at least I can still get into DSF .

Why would a military service firewall block a weapons manufacturer's website?

That's just silly.

-Siege

you've encapsulated the entire army with that last sentence.

Cool. Thanks for the replies.

I find that HK Pistol interesting. Looking at the tech specs it's actually a dart gun that fires using power from a battery. Would that be by EM force?

No. It's a bit less sci-fi than that. The cartridge is propelled chemically, but the trigger mechanism is electronic for various reasons. Check out US Patent 3982347. It represents a configuration of the electrical firing system that doesn't need batteries, but the principle of cartridge ignition is the same.

Ed-209a might be interested in this.

Cannon companion provides a number of good underwater weapons. The Colt M-24 water carbine hooks up to a scuba tank to maintain air pressure in the chamber and out the barrel... how well that would work in reality is, like most SR concepts, debateable.

The Gyrojet pistol and rifle, a revival of a project started in the 1970's, is one of the more effective underwater SR guns. Also, think about just using spearguns... if it'll harpoon a shark, it'll do just fine on humans, too.

Those being the ones mentioned in the first post followed by a "what else is there?"

~J

With the HK P11, you should be able to carry a few of the loaded barrel units. Kind of like the old black powder guns where some gunmen would carry several loaded cylinders (of course back then those things had a tendancy act like grenades at inconvient times...)

note: I'm talking in the SR world when I reference the P11...I think it would be a bit of a hassel for some pirate/runner to send his or her piece back to HK, Germany after every 5 clicks.

Wouldn't a sound gun be a decent idea for underwater? Heck, if the submarines are apparently killing whales, then shouldn't we be able to get people?

Though, that would be a pretty small target market for a company "Er, we spent thousand on R&D to make sound guns ... who buys them? Er, underwater security guards"

Well, you could adapt some sort of (largely superscience I'm afraid) saser into Shadowrun. SR has some pretty remarkable fantasy weapons physics so I don't see why it wouldn't work. You could use a laser but those will realistically attenuate VERY quickly in the water, even everyone's favorite "blue-green" versions.

Rather then underwater guns (which if you look are really just glorified spearguns) you could try small minitorpedoes. You're probably not going to get very good performance until you get to 60mm+ but they can at least theoretically be guided and carry a explosive punch.

Supercavitating weapons do not exist in Shadowrun at last check, so that rules out the best opportunity for underwater/air-water boundary projectile weapons.

I hate to be a walking advertisement, but I do suggest checking out Transhuman Space: Under Pressure for advanced underwater equipment, rules, and general technology.