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Originally Posted by benz72
Does your amazingly pressure resilient dragon bone have a constant bore diameter? Or can it be 'machined' to have one?
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You can use necromancy to Shape Bone in order to make a tube of a certain size and a bullet cast of the same size.
Quote:
Originally Posted by benz72
All the ballistics I've ever looked at assumes that the projectile has a good seal against the barrel and there is a known leak rate function (which can be idealized as 0... hey it's magic, why not?).
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Because this will probably be a muzzleloading smoothbore, there will be windage between the bullet and bore.
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Originally Posted by benz72
As to what kind of recoil / damage a given ST can support, why not just model it on the recoil & St numbers for other firearms?
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Because most TL4 and TL5 firearms, the ones that use REF 0.4 to REF 0.5 gunpowder, were limited by the reliability of metallurgy. You couldn't load them to high pressures because they'd be dangerous to the user.
Quote:
Originally Posted by benz72
For a first pass, the critical decisions should (IMO) be chamber pressure (P), bore (Axc), barrel length (L) and projectile mass(M). This should give you approximations of F=P*Axc=M*a, allowing a final V for a known L. V, with M, gives both momentum and kinetic energy (at the muzzle), which are needed to figure out range and collision characteristics.
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I can use Douglas Cole's spreadsheet to figure out the damage and range based on these factors, yes.
What I need to know is how much recoil impulse is plausible to assume that a ST 12 man can handle? If we're using a ca 15mm diameter, 300 grain spherical bullet (or 12mm, 150 grain, whichever works out with the best GURPS stats) with enough windage to avoid having to take extra time to load a muzzleloading smoothbore pistol, how fast can we propel it with REF 0.5 powder without making it more than ST 12? How long does our barrel need to be to get that kind of velocity? How much improvement do we see if we use the same bore and bullet, but make it a rifle with a longer barrel?
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Originally Posted by benz72
If these numbers make it too powerful, apply leakage past the projectile or a time-pressure profile to tone things down a bit.
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Since the´PCs can make Wands of 6d Explosive Fireballs fairly trivially, I'm not all that worried about the damage of a dragonbone pistol. But if it doesn't meet certain performance minimums, they'll simply not bother with it.