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Old 03-08-2021, 01:11 PM   #21
Varyon
 
Join Date: Jun 2013
Default Re: Plausibility check for mixed TL3/4+2 firearm

Quote:
Originally Posted by johndallman View Post
This sounds simpler than trying to create percussion caps with marginal technology. Two things that could improve the process:
  • Soak the paper in a potassium nitrate (saltpetre) solution and let it dry before making up the cartridges. This ensures the paper burns up fully, so that you don't have embers in the barrel, hiding under fouling, waiting to ignite the next cartridge when you load it.
  • Coat the finished cartridges in "waterglass," if you can get it. This makes them more robust, and can be used as a glue to hold the paper wrapping together.
Consider these ideas stolen. In fact, while I had rejected my original idea (which essentially involved a closeable breech with a built-in hollow needle, to puncture the cartridge when the breech was closed; I rejected it on the realization the built-in needle would be difficult to make and probably break upon firing), I may well revisit it to make a weapon similar to the one from OP. I'm thinking rather than a needle on a lanyard or lever or whatever, the rifleman would instead wear a ring with a needle on it. Most riflemen would have simple rings made from twisted iron wire, but wealthier/higher ranked ones would undoubtedly have more impressive rings.

Quote:
Originally Posted by Anders View Post
Fuming nitric acid is not necessary.
Even if it is, is it truly unachievable at TL4? This implies you could generate it using purified (via distillation) sulfuric acid and potassium nitrate and distilling the product. I think you could (given prior knowledge) produce the necessary reflux column (using hand pumps to run the water through it) at TL 4, albeit at great cost, and you could keep the water cold by doing it during the winter and tossing snow (or prepared ice) into your water source. Note sulfuric acid and potassium nitrate have been known for quite some time - the former as oil of vitriol and the latter as saltpeter (an ingredient in black powder).
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Old 03-08-2021, 01:47 PM   #22
TerryW
 
Join Date: Mar 2021
Default Re: Plausibility check for mixed TL3/4+2 firearm

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Originally Posted by whswhs View Post
I addressed this somewhat differently in GURPS Fantasy: Portal Realms. A quick sketch is that characters could buy anything they liked in the modern setting, but if it didn't apply in the portal realm its cost was 0 points. In particular, they could take any Wealth they liked, but they would be limited to what they were able to take with them, and that would be used to determine a new Wealth level (treating them as nomadic characters all of whose wealth was on their persons). That allowed characters to have more detailed backgrounds without having to pay points for things that are, as you say, a waste.
I showed the GM your comment and he liked it enough to use it for character creation. As a result we used more social advantages and disadvantages than we would have otherwise, so our character backgrounds are better diversified. And as part of that, the GM also decided to just start us at 150 CP (Rather than holding back 10 CP) and make us use earned CP for new social advantages and skills.

Observations from the first session:

> The Dabbler perk is great for defining a character's background abilities, stuff they should know better than most people but not really well enough to justify putting points into skills.

> GURPS sprinting rules are hilariously broken. Yes I put a lot of points into cardio fitness (HT 14, Very Fit, Breath Control 14) but doing the math we realized that my character can sprint until she collapses from hunger and thirst, or possibly sleep deprivation.

> Three advanced karate student-instructors are no match for a mob of angry peasants with gardening tools.

Again, thanks for the help everyone. I might even survive long enough to put it into action.
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Old 03-08-2021, 02:12 PM   #23
Varyon
 
Join Date: Jun 2013
Default Re: Plausibility check for mixed TL3/4+2 firearm

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Originally Posted by TerryW View Post
> GURPS sprinting rules are hilariously broken. Yes I put a lot of points into cardio fitness (HT 14, Very Fit, Breath Control 14) but doing the math we realized that my character can sprint until she collapses from hunger and thirst, or possibly sleep deprivation.
Breath Control shouldn't factor in - that's for recovering FP while resting, although that's not entirely clear from the original text (see the FAQ entry here). Without that, your effective HT 16 (14, +2 for Very Fit) will indeed prevent FP loss for a while, particularly as you only need to roll twice a minute rather than 4x a minute (thanks to Very Fit). However, on average you'll fail (rolling a 17 or 18) once every 54 attempts; assuming 14 FP, you get below 1/3 FP (and thus slow down and are exhausted) at around 540 attempts (4.5 hours) and drop to 0 FP at around 756 attempts (6.3 hours), on average falling unconscious 54 seconds later (you have to roll once per second while sprinting at 0 FP to avoid falling unconscious). Still, 4.5 hours of solid sprinting followed by 1.8 hours of exhausted jogging is incredible... but so are your character's relevant stats. Your character probably gets into the realm of outright superhuman when considering how little time it takes for her to recover from such an exhausting run, however.

Quote:
Originally Posted by TerryW View Post
> Three advanced karate student-instructors are no match for a mob of angry peasants with gardening tools.
Being outnumbered in GURPS, as in real life, is a very, very bad situation to find yourself in.
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Old 03-08-2021, 02:13 PM   #24
Fred Brackin
 
Join Date: Aug 2007
Default Re: Plausibility check for mixed TL3/4+2 firearm

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Originally Posted by TerryW View Post

> GURPS sprinting rules are hilariously broken. Yes I put a lot of points into cardio fitness (HT 14, Very Fit, Breath Control 14) but doing the math we realized that my character can sprint until she collapses from hunger and thirst, or possibly sleep deprivation.

.
Sadly, this has been known for a while.

My closest fumbling towards a solution so far is to limit characters to Sprinting for no longer than seconds equal to 4x their HT.

This would limit them to a period of time long enough to run a 400 meters but not much longer. Do not adjust that time limit for the doubling of Very Fit. We're talking anaerobic exertion and not aerobic fitness. Don't double the time you can hold your breath for Very Fit either.

Once you get past Sprint distance, paced running is broken too but it's too slow for semi-normal humans. The pace for 800 meters should be 400 meters at Sprint and another 400 meters at 3/4 speed rather than half. 1600 meters (a mile) would then add another 2 stretches of 3/4 speed.

If you don't do something like that to paced running the only way to win a marathon is to abuse the Spriintng rules. :(
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Old 03-08-2021, 02:56 PM   #25
mr beer
 
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Default Re: Plausibility check for mixed TL3/4+2 firearm

I feel like there is room for a GURPS: Olympics supplement, providing rules to map various competitive athletic feats e.g. running, swimming, weightlifting etc.
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Old 03-08-2021, 03:51 PM   #26
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Default Re: Plausibility check for mixed TL3/4+2 firearm

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Originally Posted by Anders View Post
I'll ask around at a chemistry Discord I'm on.

Edit: Fuming nitric acid is not necessary.
Nice one. Thanks for checking.
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Old 03-08-2021, 04:06 PM   #27
whswhs
 
Join Date: Jun 2005
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Default Re: Plausibility check for mixed TL3/4+2 firearm

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Originally Posted by TerryW View Post
I showed the GM your comment and he liked it enough to use it for character creation. As a result we used more social advantages and disadvantages than we would have otherwise, so our character backgrounds are better diversified. And as part of that, the GM also decided to just start us at 150 CP (Rather than holding back 10 CP) and make us use earned CP for new social advantages and skills.
I'm glad that it was helpful. I worked all this out for situations like the Pevensie kids walking into Narnia or Harold Shea transporting himself to legendary realms by contemplating formulae in symbolic logic, but the same issues seem to arise with time travel.
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Old 03-08-2021, 04:24 PM   #28
thrash
 
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Default Re: Plausibility check for mixed TL3/4+2 firearm

I've sometimes wondered if one could put a piezoelectric crystal (such as are found in modern, non-"flint" cigarette and barbecue lighters) in a firearm and use it in lieu of a percussion cap or primer.

Say you set the crystal in the end of a firing pin and place it up against an anvil inside the breach. The hammer lands on the back of the firing pin, striking a spark inside the breach.

You'd have to figure out a way to open the cartridge and expose the powder for more reliable ignition, but otherwise the breach could be sealed pretty effectively.
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Old 03-08-2021, 05:01 PM   #29
TerryW
 
Join Date: Mar 2021
Default Re: Plausibility check for mixed TL3/4+2 firearm

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Originally Posted by thrash View Post
I've sometimes wondered if one could put a piezoelectric crystal (such as are found in modern, non-"flint" cigarette and barbecue lighters) in a firearm and use it in lieu of a percussion cap or primer.
I looked into something similar, using basic dry cell batteries. Once you have the concept, batteries are easy to make with common materials. But from what I've been able to find online it's almost impossible to set off black powder with anything resembling a normal electric spark.

An alchemist or similar could easily find various concoctions that could be set off by electric sparks, but as far as I can tell all those concoctions would also be easily set off by impacts, heat, humidity, looking at them funny... Black powder is a surprisingly convenient bit of chemistry.

Plus for my character at least, it doesn't fit the concept. With her background she'd be thinking about historical examples of firearms, not electrochemical ignition. I could be wrong about not being able to set off black powder with an electric spark (it was just internet research after all) but it's not something my character would think of.
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Old 03-08-2021, 05:07 PM   #30
Varyon
 
Join Date: Jun 2013
Default Re: Plausibility check for mixed TL3/4+2 firearm

Quote:
Originally Posted by thrash View Post
I've sometimes wondered if one could put a piezoelectric crystal (such as are found in modern, non-"flint" cigarette and barbecue lighters) in a firearm and use it in lieu of a percussion cap or primer.

Say you set the crystal in the end of a firing pin and place it up against an anvil inside the breach. The hammer lands on the back of the firing pin, striking a spark inside the breach.

You'd have to figure out a way to open the cartridge and expose the powder for more reliable ignition, but otherwise the breach could be sealed pretty effectively.
This is something I've also considered. An issue here is that I believe you need fairly thin wires to produce the spark (thicker ones would spread the voltage out, so you probably wouldn't have enough to ionize the air and produce a spark - feel free to correct me if I'm wrong!), and I fear thin wires wouldn't survive the resulting explosion. Also, a bit of searching online indicates you need a pretty significant spark to ignite black powder - for example, the CVA Electra needs a high-energy capacitor and some dedicated electronics to work up enough power out of a 9V lithium ion battery to ignite the charge. In fact this guy's experiments found the easiest way to electrically ignite black powder was through using resistance heating to reach the ignition point - a typical spark just won't cut it. So, realistically, I don't think piezoelectric ignition will work. Which really sucks, because something like that would be awesome.
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