Someone suggested instead of using real world ammons I should design my own cartridges for use in customized weapons. I had a few ideas and I would love your input and ideas.

1mm Short Needle: A rather unique round based off the concept of the Guass Needler, a weapon of science fiction. Made of a high durability ceramic and propelled by a generous charge, this round slips past ballistic armor like a hot knife through butter. The damage they inflict is slight, unless vital organs are hit. Impact armor stops this Needle dead in it's tracks. For all purposes these frangible needles treat Impact Armor at double it value and hardened. Due to their small size the ammo capacity of any weapon using Needles is multiplied by 10. Can only be used in Clip fed weapons.
Damage Code: 6L
Game Effects: Ignores Balistic, Double Impact, 1/3 recoil
Special Ammo Availaibilty: None
Street Index: x2

2mm Heavy Needle: A rather unique round based off the concept of the Guass Needler, a weapon of science fiction. Made of a high durability ceramic and propelled by a generous charge, this round slips past ballistic armor like a hot knife through butter. The damage they inflict is slight, unless vital organs are hit. Impact armor stops this Needle dead in it's tracks. For all purposes these frangible needles treat Impact Armor at double it value and hardened. Due to their small size the ammo capacity of any weapon using Needles is multiplied by 10. Can only be used in Clip fed weapons.This needle can not be used in any weapon smaller than a Heavy Pistol
Damage Code: 9L
Game Effects: Ignores Balistic, Double Impact, 1/3 Recoil
Special Ammo Availaibilty: none
Street Index: x2

5mm Short: Designed as a general purpose light round. It combines ease of use, accuracy and stopping power in a small package. Useful for small game and self protection as well as target practice.
Damage Code: 7L
Special Ammo Avaialbility: All except Anti Vehicle.
Street Index: 1.1

5mm Long: Pure unadulterated speed. This little monster actually packs more propellant than bullet in weight. This allows the small round to do some serious penetration. However the round does not expand well and often shoots through the target.
Damage Code: 12L
Restricted to: Assault Rifles, Sport Rifles, and Sniper Rifles
Game Effect: Double uncompensated recoil
Special Ammo Availabilty: All except Capsule
Street Index: 1.8

9mm Pitbull: A redesign of the classic 9mm Parabellum. Using new propellants and larger slugs to make this a true combat classic.
Damage Code: 7M
Restricted to: Light Pistols and SMG's
Special Ammo Availability: All
Street Index: .8

9mm Mastiff: Inspired by the success of the PitBull the mastiff is designed for heavy hitting Assault Rifles.Unlike the 5mm Long the Mastiff combines decent velocity with heavy bullets for rounds that just hit hard.
Damage Code: 8S
Restricted to: Assault Rifles and Sporting Rifles
Game Effect: Double uncompensated Recoil.
Special Ammo Availability: All
Street index: 1.2

Feel free to submit your own ideas as this is not a complete listing of my ideas, but you never know I might like yours better.

S is still way too high for an assault rifle, IMO.

The needles strike me as unbalanced, but I can't offhand identify a good reason for it. More when I have the time to think about it.

~J

Well on the needle part, I should probably note that they treat the Impact Armor as hardened, thus the light needles bounce off Impact 3 and the Heavy Needles bounce off Impact 5 or higher. The needles are just too light to used aganist any hard armor at all.

Why would S be too high? We have several assault rifles today that fire similiarly powered cartridges. Why would militaries and gun manufacturers give that up?

The 10% recoil seems odd. For a "generous charge," I'd think that it have a closer to regular recoil. Since the big advantage of needle rounds appear to be in situations where you snuck in a concealed weapon, you could make the recoil 1/3 of normal. That way, BF with needles would only be a +1 each simple action, but it isn't the extreme that a FA only makes 1 point of recoil.

In a SMG, the needles are very dangerous as written. 19D - double impact with only a +1 from recoil. Since the most common armor gives 3 impact, that's still a 13D which is easier to pull off than a 12S from a BF heavy pistol with regular ammo.

I could go with one third recoil consider it done.

There's no way a ONE MILIMETER long needle is gonna do anything above 2L, I don't care how fast it's going. I do like the concept, though, just gimp the Power.

You should go double Recoil for the 8S assault rifle round since it's near shotgun or heavy weapon damage and these have double recoil.

The needles have a built in glaser effect, splintering inside the body. If you are wearing armor clothes, one to your heart would kill you pretty quick. Of course that takes six success over your dodge. However if you are wearing leather jacket and forearm guards they can shoot you all day. The needles will just mess up the jacket.

By the way the needle is 1mm in diameter not length. Length is more like 25mm.

Okay I am willing to double the recoil penalty for the 9mmMastif.

As for the 5mm Long, there is a reason for this. It was an experiment that didn't quite fail and didn't quite succeed. It was meant to be an Anti Vehicle munition, but it failed as the bullet design minimized the damaging effect. However it was noted that it made a great armor penetrator even with regualr ammo. Sure the damage is light but with autofire or excellent aim it can devastate an armored metahuman.

Ok, 1mm diameter still isn't going to do anywhere near 6L, even if it explodes inside of you. A light pistol round does 6L and they're way bigger than a needle.

Yes a light pistol does 6L so does a cyber grunt with STR 4 and Improved Hand Razors, so does a force 6 Light manabolt, and the list goes on. The 6L is an abstract of a not easily resisted small wound.

Honestly, a 1mm diameter projectile may cause you some long term problems (have fun trying to live with that perforated liver), but in the short term, they're not going to put you down fast enough to justify even a Light wound. The concept really isn't suited for Shadowrun's wound tracking system, and honestly, the concept isn't at all suited for any sort of small arm, either. About the only place I can see justification for such a small, ineffective projectile is use in a high rof antipersonnel minigun designed to defeat armor— sort of a Reason, only, well, less effective and less practically justifiable.

just a small nitpick.
in order to increase penetration you have upped the power level of these gauss <it is gauss btw not guass> guns, I would do it the other way..
leaving dmg level as standard-1 for the weapon , leave power as per weapon -1 <needles shoot trough people cleanly> just say that they substract a few points from armor value <so 2x impact -1 or 2x impact -2> as as they are they are a bit too deadly vs unarmored targets imho.
am also not sure about considerign impact hardened, unless you actually want the players to start using called shots to aim for unarmored parts, its hard to see any non-full cover armor as being hardened..

I think the sweet point you want is where normal ammo is better against unarmored, and needles really shine vs lightly armored foes but other types of ammo would be better against heavily armored foes.

DS

Those needle guns sort of remind me of RL flechette rifles, like the Steyr ACR. As a pistol round, I wouldn't really see a use for this ammunition, however. Still, if you want to use them in your game, go ahead.