Creating Improvised Post Apocalyptic Guns (Steampunk Post Apocalyptic Game)

[Dejavroom]

So I'm pretty well versed now In Gurps. I've been running this singular campaign for about 6 months now with little to no hitches in regards to balance with weaponry. Using the supplement "High Tech" book for Tier 5 and 6 weaponry I've got by just fine.

However I want to change things and upgrade my NPC raiders with more.. Homemade weapons. However I've never tackled any custom weaponry aside from Innate Attacks.

I'm worried about balance, Especially when it comes to scrounging for ammo using rules and the scrounging table from "After the end" And creating a threatening weapon but keeping it low power. I was wondering, Are Gurps damage values taken from the real world bullet's damage? Does it incorporate barrel length for pressure building up to increase velocity?

All these things I've been stumped with and was wondering if anyone had any advice for creating guns. I'm specifically going for the whole "Fallout" style improvised "pipe" weaponry. Utilising existing ammunition in the "High Tech" supplement like 9x19, .32 etc..

Not only are these story appropriate for me, I feel like they will give my PCs reason to spend time investing in their own improvised weaponry.



Any advice would be great!

[aaron819]

I just add the cheap modifier to TL 5 guns for "homemade" guns in After the End. Colt Navy with the Cheap modifier is a homemade .36 caliber caplock revolver, for example. Also in either Pyranid 3/88 or 3/90, you'll find stats for slamfire pipe guns. And there's a zip gun in High-Tech.

[aaron819]

3/88 also has expanded rules for black powder in reloaded bullets. Basically reducing damage and range, and making guns not made for them suck more over time if not properly maintained. It's a very good read.

[Black Leviathan]

I've built a lot of weapons for non-industrial worlds, from fantasy cartridge rifles to post-fall bench-built automatics. My loosey-goosey take is that if a gun barrel is not machined to precision specs and ammunition isn't factory uniform then it crit fails on a 16+, it's damage is reduced by -2 per die, range is cut down by 25% and weight is increased by 20%.

[Verjigorm]

If someone can find bolts and steel tubing, nd provide some sort of power, even if it's just water power, they can make a serviceable machinegun. Find some brass or copper tubing, and you're able to make lots of shells easily.

[Rupert]

Originally Posted by Verjigorm

Find some brass or copper tubing, and you're able to make lots of shells easily.

Not really. The base of the shell, with its rim and its primer pocket is the hard part, and having lots of cartridge-sized tubing doesn't help with that part.

[Fred Brackin]

Originally Posted by Rupert

Not really. The base of the shell, with its rim and its primer pocket is the hard part, and having lots of cartridge-sized tubing doesn't help with that part.

Yes, I saw a video once about how some company made their brass and it was a 14 step process including 3 trips through an annealing oven.

Then, since the words "machine gun" have been mentioned we're talkign rifle brass which means high pressures and tight tolerances as to both thickness and quality of the metal.

If we were tlakign about a black powder gatling gun the tolerances would be somewhat lower but the primers and the associated parts of the cartridge would still be quite fussy to work with.

[copeab]

Rocketball ammo doesn't need brass for a cartridge case. On the downside, it is underpowered and can have the primer or gunpowder come loose from the bullet base if handled roughly.

See the Volcanic rifle and pistol for two early examples.

[copeab]

Originally Posted by Dejavroom

Are Gurps damage values taken from the real world bullet's damage?

From muzzle energy. Very roughly, in 3e average damage was sqrtME)/2. Not sure how that holds in 4e.

[Verjigorm]

Originally Posted by Rupert

Not really. The base of the shell, with its rim and its primer pocket is the hard part, and having lots of cartridge-sized tubing doesn't help with that part.

Easy is relative. Drawing brass from cups stamped from strips of high quality brass is easy, if you've got the proper set up. It's much harder for a smaller operation to manage. On the other hand, using hydraulic presses and a variety of dies and punches to shape copper tubing is something an individual can do, as is using solder and a gas torch to "weld" copper plugs and rings to the base of the tube. If you have enough round stock and a lathe, or even just a drill press you can use an extremely wasteful method to produce shells. Quality on all these methods other than a commercial set-up is likely to be hit and miss, and reliability should be low.

The primers, fair enough, are the truly hard part. I don't really know how you would make them. I mean, I have an idea of the rough process, but I don't think I could, for example, manufacture them. The guy who knows how to make your primers would certainly be someone who should have a lot of respect in a post apocalyptic setting.

Given the tremendous advantages bolt action or semi-auto's offer over muzzle loading firearms, I'd expect that people would try to keep them operational, even if they had to kludge together haphazard solutions.