Explosive Bullets

SuedodeuS · 05-20-2009, 12:23 AM

Alternative Title: Fun ways to violate the Hague Convention.

The purpose of this thread is to make plausible guidelines for explosive bullets of various sizes, with an emphasis on small arms. High-Tech does give some general ideas of how much explosive (by bullet weight) is in each type of explosive round, which is where we'll start.

LE: HT gives a lower bound of 15%, but gives no upper bound. What should be the highest it could go? 50%? 60%? Higher still? What would be the amount of gunpowder found in a "typical" LE round? In addition, should some of the lower TL explosive rounds have a chance to fail to go off (just like SAPLE)?

SAPLE: With an upper bound of 10%, there isn't a lot to play around with. The only real question is what the typical SAPLE round would have.

APEX: Fairly straightforward, with a small range possible (upper bound 5%). The big question here (and with all HE rounds) is which high explosive is generally used at each TL? Of course, the %age of HE used in a typical APEX wouldn't be too bad to know either.

HE: HT makes reference to the LE entry. Does this mean the rounds are basically "LE, but with better explosives?" As always, the typical explosives (and amounts) used would be nice to know.

SAPHE: As with HE, this seems to be "SAPLE, but with better explosives."

SAPHEC: HT notes that these rounds tend to have around 20% weight dedicated to payload. In this case, a typical range would be nice.

APHEX: Is this basically APEX, without the decrease to basic damage? No range or average for % explosive is given.

Larger rounds: All the explosive rounds listed beyond this point have minimum calibers of at least 20mm, meaning small arms are pretty much out. However, in a recent thread, it was mentioned that there was (at least at some point) a HEAT round for a shotgun (!!!). What rounds might legitimately be able to scale down to a size usable by small arms, and would the stats end up being different in some way (notably the CPS multiplier and TL)? As always, some ideas of mass devoted to payload, explosives used, etc would be nice.

CPS: When making such rounds, should we multiply the CPS as noted and then include the cost of the explosive, or is explosive cost considered to be subsumed in the multiplier?

Damage: Determining damage for SAPHEC rounds (once you know amount and type of explosive) is easy enough - use the equation from B415. However, one would expect that, in a fragmentation explosion (which occurs in all the other cases, ignoring the larger rounds), some of the force is "wasted" creating (and throwing) fragments. Are there any good guidelines on how to make this work? Something like sacrificing 1d cr ex for [2d] is what I'm looking for here (although not necessarily those numbers).
The larger-caliber rounds make use of a different mechanism than simply "blowing up," meaning that they should probably modify the B415 rules in some manner. In the case of something like HEAT, it might be as "simple" as sacrificing some portion of the explosive damage for an increased armor divisor. Any ideas on how building these rounds should function?

These are issues that I think would be beneficial to resolve, particularly for creating new rounds (rather than using existing ones, trying to dig up their real-world statistics, and then converting these to GURPS). Unfortunately, my experience with explosives is limited to Independance Day celebrations and reading stuff online, and my experience with firearms is even less. Basically, I'm asking if anyone has already worked out some of these issues... or if they'd be willing to help me work them out!

As a final note, I understand perfectly well why these stats weren't included in High-Tech. They are likely too highly variable to be given more "screentime" than they were, as it would have likely been impossible to give them a thorough, proper treatment and still stay within page limits!

SuedodeuS · 05-20-2009, 05:25 PM

I've run some numbers trying to figure out the fragmentation issue. I analyzed 2 landmines and 4 hand grenades for the first bit. Here are the results.

OZM-3 has 75 g TNT, meaning GURPS damage 9d+2. 4d+2 is sacrificed for [4d], indicating 1d=[1d] for bounding mines. The M16, however, has 182 g TNT (GURPS damage 15d) but only 4dx2 [4d] damage, indicating a 7d=[4d] (nearly 2d=[1d]) relationship.
AMC MK II has 50 g TNT (8d-1). It sacrifices 3d+2 for [2d], which is around 2d=[1d].
StiHGr24 deals 7d, or can be inserted into a fragmentation sleeve for 5d [2d]. This is a 1d=[1d] trade-off.
M67 has 5.4 oz Composition B (13d-1). It sacrifices 4d-1 for [2d], again around 2d=[1d].
Jam-tin grenades can be 5d cr ex or 4d [2d] cr ex. This indicates 1d=[2d] for thin-shelled explosives filled with shrapnel.

We essentially have the fragmentation trade-off ranging from 1d=[2d] all the way to 2d=[1d]. Truly dedicated fragmentation (that which has preformed fragments in a thin shell) looks to lean toward 1d=[2d], semi-dedicated (shell designed to fragment) are around 1d=[1d], and incidental (explosive in shell that tends to fragment) are around 2d=[1d]. Why modern fragmentation explosives (the M16 and M67) are at the incidental area is beyond me. Regardless, I'd say that explosive rounds are somewhere in the range of the second two (probably leaning toward 2d=[1d]).

Taking these relationships, I also analyzed the artillery cannon listed in HT. I used a spreadsheet for HE and APEX rounds, assuming TNT was the explosive used (if not, divide the lb TNT entries by REF). Note that the Napoleon and Screw-Gun are included as HE - simply double lb TNT to find the amount of improved black powder (REF=0.5) in the LE shell. EDIT: I should probably mention here that the values under Cr ex and frag correspond to the dice of explosive and fragmentation damage, respectively.

Code:

HE					lb TNT	
Cannon			Cr ex	frag	1d=[1d]	2d=[1d]
Napoleon		6	5.57	0.93	2.04
Screw-Gun		6	2.71	0.53	0.91
Schneider		15	3.71	2.43	3.49
APX SA17		2	2	0.11	0.25
Rheinmetall PaK		3	2	0.17	0.34
RIA M2A1		25	5.29	6.37	8.79
Rheinmetall KwK40	21	3.71	4.24	5.61
Watervliet M1		12	3.71	1.71	2.62
DTAT MR60CS		9	3	1	1.56
Motovilikha D-81TM	36	6.29	12.42	16.38

APEX					lb TNT
Cannon			Cr ex	frag	1d=[1d]	2d=[1d]
Napoleon
Screw-Gun
Schneider		6	3.71	0.66	1.25
APX SA17		1.57	2	0.09	0.22
Rheinmetall PaK		2	2	0.11	0.25
RIA M2A1
Rheinmetall KwK40	6	3.71	0.66	1.25
Watervliet M1		5	3.71	0.53	1.07
DTAT MR60CS
Motovilikha D-81TM

Note that the subcolumns under "lb TNT" correspond to the fragmentation damage profile. If anyone happens to know the weight of each shell, and the weight of explosive (and, of course, what it is), it should be possible to back-calculate which fragmentation profile is correct.

The Napoleon and Screw-Gun, at least, can be partially analyzed now. The Napoleon fires 12-pounders, while the Screw-Gun fires 7-pounders. With the 1d=[1d] scheme, both the Napoleon and the Screw-Gun have ~16% of the projectile weight dedicated to payload (improved black powder). This is rather close to the lower bound of 15%. Using the 2d=[1d] scheme, however, the Napoleon dedicates 37.5%, while the Screw-Gun dedicates only 28.5%. Is anyone aware of which is closer to historically accurate?

~~Ragitsu~~ · 05-20-2009, 05:40 PM

I am sorry I can't be of any help, but I just wanted to say this: Good on you for integrating the Watervliet. I don't see it too often around here.

ed_209a · 05-20-2009, 08:49 PM

Quote:

Originally Posted by SuedodeuS

[b]However, in a recent thread, it was mentioned that there was (at least at some point) a HEAT round for a shotgun (!!!). What rounds might legitimately be able to scale down to a size usable by small arms, and would the stats end up being different in some way

Shotguns are smallarms, but they are 18.5mm smallarms (12 gauge are, anyway)

The big qualifier for explosive rounds is the volume of the round, and shotguns can toss BIG rounds.

A 10-ga shotgun is just a hair under 20mm bore diameter. I have wondered whether you could shave a 20mm cannon shell on a lathe and load it in a custom 10ga shell.

SuedodeuS · 05-20-2009, 09:52 PM

Quote:

Originally Posted by Ragitsu

I am sorry I can't be of any help, but I just wanted to say this: Good on you for integrating the Watervliet. I don't see it too often around here.

Honestly, I only included it because it was one of the cannons in HT that had an entry for HE (the fact it also had APEX was nice too). Thanks for the bump anyway!

Quote:

Originally Posted by ed_209a

Shotguns are smallarms, but they are 18.5mm smallarms (12 gauge are, anyway)

The big qualifier for explosive rounds is the volume of the round, and shotguns can toss BIG rounds.

A 10-ga shotgun is just a hair under 20mm bore diameter. I have wondered whether you could shave a 20mm cannon shell on a lathe and load it in a custom 10ga shell.

Good point. I know a lot of shells tend to be somewhat sub-caliber, and scootching things just a little lower to get a "20mm" HEAT shell to fit in a 10 gauge shotgun doesn't seem too far-fetched. The question still remains of if it is possible to scale such munition down further, as presumably the limits mentioned in HT are based on what's available (obviously nobody is making HEAT in 7.62x39mm!). Such rounds would likely only appear in a cinematic campaign anyway, but it would be nice to know if it's at least physically possible.

There's also the fact that, in a cinematic campaign, EFP rifle rounds would make for some very interesting "smart" munitions!

~~Ragitsu~~ · 05-20-2009, 10:37 PM

Is this "cinematic" campaign set at TL8?

SuedodeuS · 05-20-2009, 10:45 PM

Quote:

Originally Posted by Ragitsu

Is this "cinematic" campaign set at TL8?

Oh, all this is meant for general use, not just for some specific campaign. If you mean a cinematic campaign where HEAT small-arms are available, TL8 would work. EFP being used for "smart" munitions would quasi-realistically be late TL8, early TL9, although I could certainly see it being used in a mid-TL8 campaign. Eraser had TL8 gauss weapons, after all!

~~Ragitsu~~ · 05-20-2009, 11:12 PM

That is true, but I would probably call those devices a weapon technology that brinks on the beginning of TL9. Different perspectives, I suppose ;-).

ed_209a · 05-21-2009, 12:48 AM

Another issue with most smallish HE-type rounds is that as the round gets smaller, the fuze gets proportionally larger. In 40mm grenade launcher shells, for example, the fuze is nearly half the volume of the shell.

Some more recent HE rounds (notably the Raufoss Mk211) are fuseless. the impact of the round on an armored surface is enough to detonate the explosive filler.

5 minutes with Google says the Raufoss Mk211 was available in 1991. I guess that would qualify as early TL8.

Þorkell · 05-21-2009, 08:10 AM

Quote:

Originally Posted by ed_209a

5 minutes with Google says the Raufoss Mk211 was available in 1991. I guess that would qualify as early TL8.

In 4e TL8 begins in 1980.

05-20-2009, 12:23 AM	#1
SuedodeuS Join Date: Sep 2008	Explosive Bullets Alternative Title: Fun ways to violate the Hague Convention. The purpose of this thread is to make plausible guidelines for explosive bullets of various sizes, with an emphasis on small arms. High-Tech does give some general ideas of how much explosive (by bullet weight) is in each type of explosive round, which is where we'll start. LE: HT gives a lower bound of 15%, but gives no upper bound. What should be the highest it could go? 50%? 60%? Higher still? What would be the amount of gunpowder found in a "typical" LE round? In addition, should some of the lower TL explosive rounds have a chance to fail to go off (just like SAPLE)? SAPLE: With an upper bound of 10%, there isn't a lot to play around with. The only real question is what the typical SAPLE round would have. APEX: Fairly straightforward, with a small range possible (upper bound 5%). The big question here (and with all HE rounds) is which high explosive is generally used at each TL? Of course, the %age of HE used in a typical APEX wouldn't be too bad to know either. HE: HT makes reference to the LE entry. Does this mean the rounds are basically "LE, but with better explosives?" As always, the typical explosives (and amounts) used would be nice to know. SAPHE: As with HE, this seems to be "SAPLE, but with better explosives." SAPHEC: HT notes that these rounds tend to have around 20% weight dedicated to payload. In this case, a typical range would be nice. APHEX: Is this basically APEX, without the decrease to basic damage? No range or average for % explosive is given. Larger rounds: All the explosive rounds listed beyond this point have minimum calibers of at least 20mm, meaning small arms are pretty much out. However, in a recent thread, it was mentioned that there was (at least at some point) a HEAT round for a shotgun (!!!). What rounds might legitimately be able to scale down to a size usable by small arms, and would the stats end up being different in some way (notably the CPS multiplier and TL)? As always, some ideas of mass devoted to payload, explosives used, etc would be nice. CPS: When making such rounds, should we multiply the CPS as noted and then include the cost of the explosive, or is explosive cost considered to be subsumed in the multiplier? Damage: Determining damage for SAPHEC rounds (once you know amount and type of explosive) is easy enough - use the equation from B415. However, one would expect that, in a fragmentation explosion (which occurs in all the other cases, ignoring the larger rounds), some of the force is "wasted" creating (and throwing) fragments. Are there any good guidelines on how to make this work? Something like sacrificing 1d cr ex for [2d] is what I'm looking for here (although not necessarily those numbers). The larger-caliber rounds make use of a different mechanism than simply "blowing up," meaning that they should probably modify the B415 rules in some manner. In the case of something like HEAT, it might be as "simple" as sacrificing some portion of the explosive damage for an increased armor divisor. Any ideas on how building these rounds should function? These are issues that I think would be beneficial to resolve, particularly for creating new rounds (rather than using existing ones, trying to dig up their real-world statistics, and then converting these to GURPS). Unfortunately, my experience with explosives is limited to Independance Day celebrations and reading stuff online, and my experience with firearms is even less. Basically, I'm asking if anyone has already worked out some of these issues... or if they'd be willing to help me work them out! As a final note, I understand perfectly well why these stats weren't included in High-Tech. They are likely too highly variable to be given more "screentime" than they were, as it would have likely been impossible to give them a thorough, proper treatment and still stay within page limits! __________________ Quos deus vult perdere, prius dementat. Latin: Those whom a god wishes to destroy, he first drives mad. Last edited by SuedodeuS; 05-20-2009 at 12:26 AM.

05-20-2009, 05:25 PM	#2
SuedodeuS Join Date: Sep 2008	Re: Explosive Bullets I've run some numbers trying to figure out the fragmentation issue. I analyzed 2 landmines and 4 hand grenades for the first bit. Here are the results. OZM-3 has 75 g TNT, meaning GURPS damage 9d+2. 4d+2 is sacrificed for [4d], indicating 1d=[1d] for bounding mines. The M16, however, has 182 g TNT (GURPS damage 15d) but only 4dx2 [4d] damage, indicating a 7d=[4d] (nearly 2d=[1d]) relationship. AMC MK II has 50 g TNT (8d-1). It sacrifices 3d+2 for [2d], which is around 2d=[1d]. StiHGr24 deals 7d, or can be inserted into a fragmentation sleeve for 5d [2d]. This is a 1d=[1d] trade-off. M67 has 5.4 oz Composition B (13d-1). It sacrifices 4d-1 for [2d], again around 2d=[1d]. Jam-tin grenades can be 5d cr ex or 4d [2d] cr ex. This indicates 1d=[2d] for thin-shelled explosives filled with shrapnel. We essentially have the fragmentation trade-off ranging from 1d=[2d] all the way to 2d=[1d]. Truly dedicated fragmentation (that which has preformed fragments in a thin shell) looks to lean toward 1d=[2d], semi-dedicated (shell designed to fragment) are around 1d=[1d], and incidental (explosive in shell that tends to fragment) are around 2d=[1d]. Why modern fragmentation explosives (the M16 and M67) are at the incidental area is beyond me. Regardless, I'd say that explosive rounds are somewhere in the range of the second two (probably leaning toward 2d=[1d]). Taking these relationships, I also analyzed the artillery cannon listed in HT. I used a spreadsheet for HE and APEX rounds, assuming TNT was the explosive used (if not, divide the lb TNT entries by REF). Note that the Napoleon and Screw-Gun are included as HE - simply double lb TNT to find the amount of improved black powder (REF=0.5) in the LE shell. EDIT: I should probably mention here that the values under Cr ex and frag correspond to the dice of explosive and fragmentation damage, respectively. Code: HE lb TNT Cannon Cr ex frag 1d=[1d] 2d=[1d] Napoleon 6 5.57 0.93 2.04 Screw-Gun 6 2.71 0.53 0.91 Schneider 15 3.71 2.43 3.49 APX SA17 2 2 0.11 0.25 Rheinmetall PaK 3 2 0.17 0.34 RIA M2A1 25 5.29 6.37 8.79 Rheinmetall KwK40 21 3.71 4.24 5.61 Watervliet M1 12 3.71 1.71 2.62 DTAT MR60CS 9 3 1 1.56 Motovilikha D-81TM 36 6.29 12.42 16.38 APEX lb TNT Cannon Cr ex frag 1d=[1d] 2d=[1d] Napoleon Screw-Gun Schneider 6 3.71 0.66 1.25 APX SA17 1.57 2 0.09 0.22 Rheinmetall PaK 2 2 0.11 0.25 RIA M2A1 Rheinmetall KwK40 6 3.71 0.66 1.25 Watervliet M1 5 3.71 0.53 1.07 DTAT MR60CS Motovilikha D-81TM Note that the subcolumns under "lb TNT" correspond to the fragmentation damage profile. If anyone happens to know the weight of each shell, and the weight of explosive (and, of course, what it is), it should be possible to back-calculate which fragmentation profile is correct. The Napoleon and Screw-Gun, at least, can be partially analyzed now. The Napoleon fires 12-pounders, while the Screw-Gun fires 7-pounders. With the 1d=[1d] scheme, both the Napoleon and the Screw-Gun have ~16% of the projectile weight dedicated to payload (improved black powder). This is rather close to the lower bound of 15%. Using the 2d=[1d] scheme, however, the Napoleon dedicates 37.5%, while the Screw-Gun dedicates only 28.5%. Is anyone aware of which is closer to historically accurate? __________________ Quos deus vult perdere, prius dementat. Latin: Those whom a god wishes to destroy, he first drives mad. Last edited by SuedodeuS; 05-20-2009 at 06:39 PM.

05-20-2009, 05:40 PM	#3
~~Ragitsu~~ Banned Join Date: Dec 2007 Location: Portland, Oregon	Re: Explosive Bullets I am sorry I can't be of any help, but I just wanted to say this: Good on you for integrating the Watervliet. I don't see it too often around here.

05-20-2009, 10:37 PM	#6
~~Ragitsu~~ Banned Join Date: Dec 2007 Location: Portland, Oregon	Re: Explosive Bullets Is this "cinematic" campaign set at TL8?

05-20-2009, 11:12 PM	#8
~~Ragitsu~~ Banned Join Date: Dec 2007 Location: Portland, Oregon	Re: Explosive Bullets That is true, but I would probably call those devices a weapon technology that brinks on the beginning of TL9. Different perspectives, I suppose ;-).

05-21-2009, 12:48 AM	#9
ed_209a Join Date: Sep 2004	Re: Explosive Bullets Another issue with most smallish HE-type rounds is that as the round gets smaller, the fuze gets proportionally larger. In 40mm grenade launcher shells, for example, the fuze is nearly half the volume of the shell. Some more recent HE rounds (notably the Raufoss Mk211) are fuseless. the impact of the round on an armored surface is enough to detonate the explosive filler. 5 minutes with Google says the Raufoss Mk211 was available in 1991. I guess that would qualify as early TL8. __________________ “Civilized men are more discourteous than savages because they know they can be impolite without having their skulls split, as a general thing.” - Robert E Howard, "The Tower of the Elephant"

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode