Modern Monster Hunting Guns [XM500, MICOR Leader 50, etc.]

[Rupert]

Note that if you want more power from a 12-gauge shotgun, you buy one that will take 3" shells, as well as 2-3/4" shells. That strongly suggests that a 2-3/4" shell lacks the capacity for both a heavy payload and enough powder to drive it at full velocity.

If you are really confident of your gun's strength, you could load the shells with a faster burning powder, but if you get this wrong you will damage your gun, and possibly yourself as well. Besides, faster burning powders will only herlp so much, especially in a long barrelled weapon.

[lwcamp]

Originally Posted by Icelander

Assuming that PCs want to use 12G shotgun slugs with a very large cavity, to fit various exotic anti-supernatural menace substances in, a 1 oz. hollow-cavity slug might be almost as long as a more solid 1.5 oz. slug.

What does that do to the remaining space for powder in a 2.75" shell?

Is the velocity of commercial slug ammunition close to the theoretical maximum of the performance you can get at the size and pressure of 2.75" 12G shotgun shells or could you load the shells with more powder, even with a projectile the size of a 1 3/8 oz. slug?

In other words, would using large hollow-cavity slugs inevitably mean losing velocity due to powder space concerns or are typical shotgun shells larger than they need to be for modern powders anyway, with lack of demand for hard-recoiling loads the reason shells aren't often packed to full capacity with powder and projectile?

Is there any reason not to put one of your custom loads into a 3" or 3.5" shell?

In any case, go to Google Images and search for shotgun slug cross section
https://www.google.com/search?hl=en&...30.WaBhBdkEdoE
It looks like a bit of space is taken up by the wad. I'm not enough of an armorer to tell you what skimping on the wad will do.

Luke

[Fred Brackin]

Originally Posted by lwcamp

Is there any reason not to put one of your custom loads into a 3" or 3.5" shell?

In any case, go to Google Images and search for shotgun slug cross section
https://www.google.com/search?hl=en&...30.WaBhBdkEdoE
It looks like a bit of space is taken up by the wad. I'm not enough of an armorer to tell you what skimping on the wad will do.

Luke

If the altered wad you end up with is actually inadequate you could lose gas sealing and you might not even get your payload out of the barrel. The wad is what makes the seal.

[Icelander]

Originally Posted by lwcamp

Is there any reason not to put one of your custom loads into a 3" or 3.5" shell?

For 3.5" shells, it's because it's hard to find a modern tactical shotgun with a decent capacity and the ability to mount the accessories that PCs tend to want that chambers 3.5" shells. I am open to suggestions, though.

One player has already stated that he wants a 3" shell shotgun, for added power firing custom handloads. However, given that some of the high-capacity sci-fi shotguns available these days, like the Mossberg 590M or the Fostech Origin 12, only chamber 2.75" shells, I'll have to stat a version of the load for such weapons.

[Icelander]

Originally Posted by Icelander

Wow, I didn't even know that existed!

I thought the weapon in 'Chappie' was fictional.

From a private message, reproduced here with kind permission.

I guess importing Inkunzi PAW-20 grenade launchers to the US would be fairly difficult, even for a Patron with extreme resources who employs Class 3 FFL gunsmiths and has connections with sheriffs. Of course, there is always a straw purchase through a Private Security Company headquartered on a friendly Caribbean island with an obliging official in charge of licensing.

[Rupert]

Originally Posted by lwcamp

Is there any reason not to put one of your custom loads into a 3" or 3.5" shell?

In any case, go to Google Images and search for shotgun slug cross section
https://www.google.com/search?hl=en&...30.WaBhBdkEdoE
It looks like a bit of space is taken up by the wad. I'm not enough of an armorer to tell you what skimping on the wad will do.

Reduce accuracy, possibly increase chamber pressure, damage the payload, and possibly also damage the gun's bore.

[Icelander]

Originally Posted by Rupert

Note that if you want more power from a 12-gauge shotgun, you buy one that will take 3" shells, as well as 2-3/4" shells. That strongly suggests that a 2-3/4" shell lacks the capacity for both a heavy payload and enough powder to drive it at full velocity.

That sounds plausible. On the other hand, Googling suggests that 3" shells are not regarded by many people as substantially more powerful, certainly not enough so to justify the added recoil and lack of magazine capacity, and that there is a school of thought that regards them as outdated with improvements in ammunition technology. That is, they are very useful for firing steel shot, when you need the extra space, but they do not add much, if anything, to tactical utility.

Certainly, the 3" shells will have a higher ceiling for velocity and projectile weight, but given that driving slugs faster than 1500 fps or so appears to yield diminishing returns and I've not found anything faster than 1800 fps, it's possible that the difference between 2.75" and 3" shells might only amount to about a 50-150 fps.

Given that in the real world, driving a hollow-cavity slug to the maximum velocity possible is hardly a common design goal, I thought I'd ask for some assistance in the principles behind it.

Edit: I've even found 12G 2.75" shells loaded with 1 1/4 oz. and 1 3/8 oz. slugs, with handloaders claiming they've been able to load even heavier (and thus longer) shells. Yes, it is true that 1000 grain slugs can only be loaded in 3" or longer shells, but it seems that getting 1 oz. slugs even with a hollow-cavity that reduces weight by 25% is entirely practical even with 2.75" shells.

This means that all PCs and their NPC allies can use the same custom slugs as a delivery system for exotic anti-supernatural substances, with differences, if any, being in the powder charges behind them. Which is likely to be a fast-burning load optimized for short barrels and an extra-powerful load for the 3" shells used by the 6'6", 300 lbs. PC.

The 3" shells are more interesting in that they allow more pellets to be loaded, which might be nice for 'cold iron' shot loads for faerie creatures and/or silver shot loads for other creatures.

Originally Posted by Rupert

If you are really confident of your gun's strength, you could load the shells with a faster burning powder, but if you get this wrong you will damage your gun, and possibly yourself as well. Besides, faster burning powders will only herlp so much, especially in a long barrelled weapon.

There are enough resources involved so that the weapons can be bought new, well-maintained and worked on by a skilled gunsmith. Basically, Fine (Reliable) modifications will be made if possible and the shotguns will hopefully be high quality to start with.

Faster burning powders are something that I was wondering about. The PCs might have shotguns with barrels ranging from 6.5" to 18.5" and it would help if the ammunition for the concealable backup weapons were optimized for shorter barrels.

[Icelander]

I set my new campaign in the modern day and allowed the PCs to have a billionaire Patron, hold positions as Reserve Deputy Sheriffs, own firearm trusts and belong to a Private Security Contractor with associated Class III dealers, so the PCs would have top-of-the-line modern firepower for their monster hunting.

Only for all the PCs to take spellcasting ability (which in a Dresden Files -esque way interferes with high-tech stuff) and the most modern firearms chosen to be a bolt-action rifle (A-Square Hannibal .577 Tyrannosaur) and a pump shotgun (Kel-Tec KSG-25). I thought for sure that some players would elect to play one of the former SOF operators employed to provide close protection for the academics and investigators whomtheir Patron sends out troubleshooting, not to mention shooting trouble when they find it. But no, the closest thing to SOF operator is a guy who was in French Foreign Legion in the 80s and since then, he's been lost in time and space and picked up strange magics.

So, instead of custom-made big bore ARs, compact .50 BMG rifles and semi-automatic .338 Lapua Magnums, it'll be 12G slugs and maybe the occasional 750 grain .577 Tyranosaur bullet.

Which brings me to my question. How big a volume of a 12G slug or huge 750 grain bullet can one leave as a hollow cavity for payload before it gets implausible?

Assume a gifted armourer with professional assistants and a workshop suitable for custom gunsmithing, as well as the kind of machines for loading ammunition that a small manufacturing concern for premium match ammunition might have.

While the payload will be stuff like hawthorn, rowan, salt, silver nitrate, wolfsbane, etc. instead of explosive or incendiary filler, this is still probably best approached as an analogue to big bore smallarm rounds like the Raufoss .50 BMG (longer than the .577 Tyrannosaur, but a ball .50 BMG weighs the same as the shorter and stubbier .577 bullet) or a very small grenade launcher.

Does anyone know how much of the volume of big bore smallarm rounds that are explosive or incendiary is payload?

What about gimmicky 12G slugs in SAPHE, APHEX or the equivalent?

[johndallman]

Originally Posted by Icelander

Does anyone know how much of the volume of big bore smallarm rounds that are explosive or incendiary is payload?

Well, here's a diagram of the Raufoss Mk211. The important thing about it is that it has no fusing mechanism, which would take up a lot of space. When it hits, the tungsten carbide penetrator moves forwards under its own inertia, which sets the other parts off. Modern Firepower for 3e describes how this works; High-Tech for 4e calls it APHEX (p. 170).

For non-explosive payloads, the problem is getting the bullet to open up and disperse its payload. That's dealt with under Hollow-Point and Poison rounds, on pp. 166-7 of High-Tech.

[Icelander]

Originally Posted by johndallman

Well, here's a diagram of the Raufoss Mk211. The important thing about it is that it has no fusing mechanism, which would take up a lot of space. When it hits, the tungsten carbide penetrator moves forwards under its own inertia, which sets the other parts off. Modern Firepower for 3e describes how this works; High-Tech for 4e calls it APHEX (p. 170).

To me, that looks like about a third of the volume devoted to payload, that is, incendiary and explosive materiel.

Does it look like more or less than a third to you?

Originally Posted by johndallman

For non-explosive payloads, the problem is getting the bullet to open up and disperse its payload. That's dealt with under Hollow-Point and Poison rounds, on pp. 166-7 of High-Tech.

Indeed so. I'm just looking for more detail, so that .22 LR, .45 ACP, .577 Tyrannosaur and the longest possible 12-gauge shell don't all have the same space in a hollow-cavity for a non-explosive payload.

Currently, I'm working off the rule of thumb that with a custom hollow-point design where the cavity is much larger than in modern bullets where good expansion is the only goal, a .45 ACP can deliver .25 mL of payload, or about one dose of many common poisons, which I'll generalise to substances that affect the paranormal. That will be a 200 grain bullet that is as long as 255 grain lead bullets for .45 LC or .45 ACP loads.

Longer .452 bullets meant for rifles can have a deeper cavity, with 0.5 mL payload being standard for the .450 Bushmaster and 45 Raptor loads that the former SOF operators who handle security for the PCs' Patron will use against curious critters. That's a bullet that would be 395 grains if solid, but in hollow-cavity design it's 280 grains. As a bonus, these bullets can be loaded in .460 S&W loads for revolvers, which one PC, Lucien Lacoste, is actually taking advantage of.

I was considering their standard anti-monster 12-gauge slugs being designed for .75 mL cavities, with the possibility of a very, very long slug that required a brass 3" shell (and packed the powder too tight for any commercial manufacturer to consider) which could hold 1 mL of payload.

Purely by weight, the .577 Tyrannosaur bullets are between normal 12-gauge slugs and the larger ones. I suppose that if my initial estimate for the .45 ACP was not wildly implausible and scaling the design up works, it might plausibly enough rate a .75 mL cavity, with a possibility existing for a 1 mL version, but that would mean a lighter powder charge and/or a light for its caliber bullet that deformed very quickly, in either case reducing penetrating Dmg more compared to a less extreme design, which should only reduce it as expanding bullets usually do (I use Doug Cole's calculations for that).