If i used a lower arm as a SMG, would i use the arm's agility or my agility?

The rules seem to indicate that with partial limbs, the stat of the partial limb rarely applies. If you put an smg into a lower arm, it seems like 100% of the aiming would be handled by the shoulder and upper arm, since the barrel would have to be set along your lower arm bones and out your palm, so no aiming with those parts would be possible. I 100% say your agility.

OSUMacbeth

For this reason, I think a partial cyberlimb can be the best of both worlds. Most of the advantages of the cyberarm, few of the penalties. I myself have my commlink, Ultrasound, datajack, and a cyberarm gyromount in mine, and am loving it.

OSUMacbeth

huh? that makes no sense. your cyber-SMG is going to be below your elbow, right? that means that your forearm is going to be instrumental in aiming the thing.

Not true; the forearm is moved by muscles in the upper arm in the human body. The hand is controlled by the forearm, mainly.

OSUMacbeth

i guess it depends on whether you see it as including the elbow or not. if not, i'd think your upper arm is going to tire out pretty quick, having to shove all that chrome around.

A good point; assuming your arm didn't adapt and become stronger, you'd want some kind of actuator in the elbow, most likely. I still think the quickness of the forearm shouldn't count, but as with many of the rules in sr4, it seems to come down to gm fiat.

OSUMacbeth

What is the canon weight for a cyberform and how does it compare to a meat forearm?
Prostetic limbs tend to be very lightweight. I see no reason why this trend shouldn't continue.

Prosthetic limbs may be lightweight currently, but do prosthetic limbs include the components to move, do they actually have synthetic muscles? As far as I know they do not, that means the futuristic cyberlimb will almost certainly be heavier than a modern day prosthetic because of its extra components, but I don't see why it would be significantly heavier than a normal human limb. I seem to recall there being weights for cyberware back in 1st Edition, but I can't recall seeing any weights for cyberware of any kind since then.

there are fibers out there that act just like muscles when exposed to current.

Really, I think the term "chrome", when applied to cyber-limbs, is kind of a mis-nomer. Really, unless you have armor on the thing (and even then its unlikely), very little, if any, of the limb is made of metal.

Pretty much the entire thing would be made of plastics and possibly ceramics. For the simple reason that metal would be too heavy. Most all the "metal" looking cyber-arms and what not are likely just silver colored plastic.

Of course, you might think that these materials arent strong enough, but I beg to differ. Remeber, this is quite far in the future. It is not unreasonoble to believe that the "super" ceramics and polymers have been developed fully. Also, all the wiring would be fiber-optics. Super high strength cyber-limbs might have some kind of alloy skeletal structure, but those are mounted on a cyber-torso, so the weight is less of an issue.

My bet is that a normal cyber-arm weighs no more or less than the natural arm its replacing. Anything else would throw off the bodys balance, and possibly over-stress the shoulder.

Erm, just to be the devil's advocate, how do we know that metallurgy hasn't progressed to the point where a sturdy lightweight alloy for cyberlimbs hasn't been invented yet? Also, there is a possibility of plastic/ceramic and metal hybrids. It doesn't have to be excessively cheap (after all, cyberlimbs are worth a mint), either. State-of-the-art Nano Age materials = SOTA credstick debt.

Good point, it is possible that parts of the cyber-limbs are made of advanced super alloys. I guess that all comes down to preference.

However, I think that irregardless of the material, the weight of the arm (or whatever) is going to be the same as the limb its replacing in most all cases. (tie a 5lb dumbell onto one arm and walk around like that for a day, see how your shoulder feels =)