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Old 03-11-2018, 04:28 PM   #282
Join Date: Mar 2013
Default Re: Magico-alchemical ignition

Originally Posted by Icelander View Post
One PC is receiving a set of magical pocket pistols in a 'deringer' style, made out of orichalum with double barrels 3" long. The grip of one of pistol is made from shark's tooth and the grip of the other from mother of pearl. The former pistol is decorated with engravings of the PC defeating divine emissaries of their enemies and defending his men from sharks in the ocean and the other pistol has him fighting beside sahuagin (shark men) against the nobles, priests and generals of the other side.

The weapons carry various enchantments, but the ones I'd like to get help with are the ones that ignite the smokepowder and are meant to get the most of the propellant in a short barrel.

Pulling the trigger activates an Essential Air spell to fill the barrel with the essence of oxygen and ensure rapid burning of the propellant and simultaneously causes the 3 FP version of the Ignite Fire spell to go off in the entire barrel, the equivalent of a blowtorch being applied to the 25 grains of finely-ground REF 0.8 smokepowder (about mid-way in REF between high-quality black powder and TL6 smokeless powder). A Shape Air spell ensures optimum mixing of the burning propallant and the Essential Air while the combustion is going on.

This propels a 10mm 90 grain lead and antinomy ball out the barrel. The orichalum construction means that there is no risk of catastrophic overpressure despite the near instant detonation of the smokepowder. I figure that it could use a larger powder charge, but as it's so tiny and the grip only allows three fingers, we want to avoid too much of a kick.

I can use Doug Cole's spreadsheet to find the stats, but I need to know what would be reasonable in terms of PSI, burn length and, derived from that, the muzzle velocity.

What would be a reasonable figure for muzzle velocity? 1,200 fps? 1,500 fps? 2,000 fps? 3,000 fps?
Too complicated for a start, and if I was GMing I'd say that the Ignite Fire results in the barrel heating up, dropping your rate of fire. Really what you want is Fast Fire cast on the ammo.
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