Steve Jackson Games - Site Navigation
Home General Info Follow Us Search Illuminator Store Forums What's New Other Games Ogre GURPS Munchkin Our Games: Home

Go Back   Steve Jackson Games Forums > Roleplaying > GURPS

Reply
 
Thread Tools Display Modes
Old 02-15-2020, 04:19 PM   #1
Michael Thayne
 
Michael Thayne's Avatar
 
Join Date: May 2010
Default [High-Tech] [Ultra-Tech] Ultra-Tech style write-ups of TL5-8 ammo

The point of this thread is similar to the point of my previous thread on TL 5-8 firearms in Ultra-Tech calibers. High-Tech's approach to various ammo types is not very standardized and in some cases requires hauling out a calculator, so I thought it would be nice to write up an alternative system.

In this post, I'm going to focus on the main options for pistol and rifle rounds. I'll do grenades and missile warheads in a later post.

Extra-Powerful (+P) Ammunition

Divide dice of damage by 3, round to the nearest whole number, and apply the result as a damage bonus. Effects on things other than damage are unchanged.

Match-Grade Ammunition

Unchanged.

Subsonic Ammunition

Existing rules are okay I guess but if you want a simpler rule using -1 to damage regardless of gun type would make sense. Not sure if that should be worth a -1 or -2 penalty to hearing rolls. Other aspects would be unchanged.

Silent Ammunition

Unchanged.

Solid

If you're using "UT style" write-ups for all firearm types, solid ammo will be standard even for shotguns, so this option can be ignored.

Hollow-Point (HP)

Largely unchanged. If you care about consistency with Ultra-Tech you might ignore the "targets with DR 0 get DR 1 instead" rule, or declare that that rule applies to TL9 hollow-points too. Or you could decide that's a perk of using ultra-tech ammo. Unchanged, as Rupert points out below.

Armor-Piercing

Change effect on damage to -1 per die. Otherwise unchanged.

Armor-Piercing Hardcore (APHC)

Unchanged. Interestingly the rules for TL6 APHC ammo are basically identical to those for TL9 APHC ammo. I guess Ultra-Tech didn't want to put lower TL numbers anywhere even where they would have made sense.

Armor-Piercing Discarding-Sabot (APDS)

Use the rules in Ultra-Tech.

Baton, Beanbag, SAPFSDS, UD

Unchanged.

Depleted Uranium

APEP is supposed to be Ultra-Tech's equivalent of depleted uranium rounds but High-Tech gives a more more finely differentiated set of options. I need to think about how to handle this, and would appreciate thoughts in comments.

Last edited by Michael Thayne; 02-15-2020 at 07:22 PM.
Michael Thayne is offline   Reply With Quote
Old 02-15-2020, 05:46 PM   #2
Rupert
 
Rupert's Avatar
 
Join Date: Aug 2004
Location: Wellington, NZ
Default Re: [High-Tech][Ultra-Tech] Ultra-Tech style write-ups of TL5-8 ammo

Quote:
Originally Posted by Michael Thayne View Post
Subsonic Ammunition

Existing rules are okay I guess but if you want a simpler rule using -1 to damage regardless of gun type would make sense. Not sure if that should be worth a -1 or -2 penalty to hearing rolls. Other aspects would be unchanged.
As almost none of the ammo in UT will be subsonic, and the rifle calibre rounds will (aside from the payload rifle) be very supersonic, all reducing the damage of the rifle rounds by -1/die would do is give them less damage and range. It wouldn't reduce their report usefully.
Quote:
Hollow-Point (HP)

Largely unchanged. If you care about consistency with Ultra-Tech you might ignore the "targets with DR 0 get DR 1 instead" rule, or declare that that rule applies to TL9 hollow-points too. Or you could decide that's a perk of using ultra-tech ammo.
Or you could stick with the RAW - when you look up an armour penetration modifier of (0.5), you end up at B110, and it explains how it works. Why would UT's hollow points, etc., work differently?
__________________
Rupert Boleyn

"A pessimist is an optimist with a sense of history."
Rupert is offline   Reply With Quote
Old 02-15-2020, 07:20 PM   #3
Michael Thayne
 
Michael Thayne's Avatar
 
Join Date: May 2010
Default Re: [High-Tech][Ultra-Tech] Ultra-Tech style write-ups of TL5-8 ammo

Quote:
Originally Posted by Rupert View Post
As almost none of the ammo in UT will be subsonic, and the rifle calibre rounds will (aside from the payload rifle) be very supersonic, all reducing the damage of the rifle rounds by -1/die would do is give them less damage and range. It wouldn't reduce their report usefully.
As discussed in my previous thread, the the default TL9 UT firearms do not appear to be any more powerful than their TL7-8 equivalents. Certainly subsonic ammo should not be available for electrothermal-chemical weapons or liquid propellant slugthrowers. You do have somewhat of a point about realism—High-Tech says the subsonic option should multiply damage by 0.8 for pistol rounds and 0.6 for rifle rounds, a flat -1 per die for all weapon types would be a decision to sacrifice realism for simplicity.

Quote:
Or you could stick with the RAW - when you look up an armour penetration modifier of (0.5), you end up at B110, and it explains how it works. Why would UT's hollow points, etc., work differently?
Oh shoot, I was wondering if there was a rule like that, but I somehow failed to find it.
Michael Thayne is offline   Reply With Quote
Old 02-15-2020, 07:53 PM   #4
Fred Brackin
 
Join Date: Aug 2007
Default Re: [High-Tech][Ultra-Tech] Ultra-Tech style write-ups of TL5-8 ammo

Quote:
Originally Posted by Michael Thayne View Post
Oh shoot, I was wondering if there was a rule like that, but I somehow failed to find it.
The assumed armor value for human skin of 0.5 can be hard to find and I tend to ignore it because I don't believe it to be accurate. It would make shoe leather (DR1) only twice as tough as bare skin.

I'd put the armor value of bare human skin at something more like DR 0.2.
__________________
Fred Brackin
Fred Brackin is offline   Reply With Quote
Old 02-15-2020, 10:37 PM   #5
Michael Thayne
 
Michael Thayne's Avatar
 
Join Date: May 2010
Default Re: [High-Tech][Ultra-Tech] Ultra-Tech style write-ups of TL5-8 ammo

Now for rounds typically fired as grenades, etc. Generally, explosive damage scales with cube root of weight which holding shape constant is equivalent to (linear dimension)^(1.5). Shaped charges, however, don't seem to follow the usual rules for explosions—instead they just scale with linear dimension. Smoke grenades should have radius of effect scale with linear dimension.

High-Explosive

TL6-8 high explosive rounds use the stats of the TL9 version but use the following table for damage:

10mm: 1d-1 cr ex [1d-2]
15mm: 1d+2 cr ex [1d-1]
18.5mm: 2d cr ex [1d]
25mm: 3d+1 cr ex [1d+1]
40mm: 6d+2 cr ex [2d]
64mm: 6dx2 cr ex [3d]
100mm: 6dx4 cr ex [5d]

These numbers were derived by using a 40mm grenade as a baseline. They're a little over 80% of the numbers at TL9.

High-Explosive Concussion

As high-explosive but without fragmentation damage.

Shaped Charge

Shaped charge warheads become available at TL7. For 18.5mm shaped charge, use the HEAT shotgun round on High-Tech p. 103 (unavailable before TL8). For 25mm shaped charge, see the GD M307 (High-Tech pp. 144-145, I'm guessing also unavailable before TL8). For 40mm shaped charge, see HEDP on High-Tech p. 143. Larger calibers do the following damage from mid-TL7ish through TL8:

64mm: 6dx3(10) cr ex + linked 8dx2 cr ex [3d]
100mm: 6dx5(10) cr ex + linked 8dx4 cr ex [5d]
Michael Thayne is offline   Reply With Quote
Old 02-16-2020, 09:23 AM   #6
Varyon
 
Join Date: Jun 2013
Default Re: [High-Tech][Ultra-Tech] Ultra-Tech style write-ups of TL5-8 ammo

Quote:
Originally Posted by Michael Thayne View Post
Extra-Powerful (+P) Ammunition

Divide dice of damage by 3, round to the nearest whole number, and apply the result as a damage bonus. Effects on things other than damage are unchanged.
For those who don't want to do math, you can do it as 2d-4d is +1, 5d-7d is +2, 8d-10d is +3, etc. That is, drop adds, every 3d is +1 with an error of +1d.

Quote:
Originally Posted by Michael Thayne View Post
Depleted Uranium

APEP is supposed to be Ultra-Tech's equivalent of depleted uranium rounds but High-Tech gives a more more finely differentiated set of options. I need to think about how to handle this, and would appreciate thoughts in comments.
UT's APEP is the equivalent of APDSDU. I'd suggest maintaining the HT options (and indeed allowing the enhanced penetrator option from UT to be split into the equivalents of APDU, APDSDU, and APDSFSDU would be appropriate). Personally, I favor the HT treatment (enhanced damage and lesser armor divisor, which works out to the same armor penetration).

Quote:
Originally Posted by Michael Thayne View Post
Certainly subsonic ammo should not be available for electrothermal-chemical weapons or liquid propellant slugthrowers.
ETC should be able to make use of subsonic (the bullets would just have less propellant), although the damage would be reduced based on the pre-ETC damage. LP already has subsonic built in as an option (it's the Low Velocity option). What shouldn't be available for either, or indeed for any caseless weapon, is Silent, as this makes use of a specially-designed case.

Quote:
Originally Posted by Michael Thayne View Post
You do have somewhat of a point about realism—High-Tech says the subsonic option should multiply damage by 0.8 for pistol rounds and 0.6 for rifle rounds, a flat -1 per die for all weapon types would be a decision to sacrifice realism for simplicity.
-1/die is right around a 0.7 multiplier (it's actually something like 0.715), and is indeed an acceptable simplification if you're willing to sacrifice some resolution. Personally, I like that pistols are less affected than rifles.

Quote:
Originally Posted by Michael Thayne View Post
High-Explosive

TL6-8 high explosive rounds use the stats of the TL9 version but use the following table for damage:

10mm: 1d-1 cr ex [1d-2]
15mm: 1d+2 cr ex [1d-1]
18.5mm: 2d cr ex [1d]
25mm: 3d+1 cr ex [1d+1]
40mm: 6d+2 cr ex [2d]
64mm: 6dx2 cr ex [3d]
100mm: 6dx4 cr ex [5d]

These numbers were derived by using a 40mm grenade as a baseline. They're a little over 80% of the numbers at TL9.
For explosives, they should really improve at every TL, as REF of contemporary explosives go up. Roughly speaking, and assuming REF is 2 at TL8, 1.5 at TL7, and 1 at TL6, you're looking at x0.85 to damage at TL 7, x0.7 damage at TL 6. Call the former -1 per 2d, the latter -1 per 1d. If you want to go lower, TL 5 is probably REF 0.5 (x0.5), TL 4 is REF 0.4 (x0.45), and TL 3 is REF 0.3 (x0.4), all of which would count as -2 per 1d.

Quote:
Originally Posted by Michael Thayne View Post
High-Explosive Concussion

As high-explosive but without fragmentation damage.
Fragmenting explosives "use up" some of their power producing and propelling fragments, so those designed to not produce fragmentation (like thin-shelled HEC rounds) should do more damage. Roughly speaking, fragmentation tends to be around 1d per 20mm (which matches up well with your values), and every 2d of fragmentation generated "costs" 1d of explosive damage. So, using your numbers, HEC would be:

10mm: 1d cr ex
15mm: 2d-1 cr ex
18.5mm: 2d+2 cr ex
25mm: 4d-1 cr ex
40mm: 7d+2 cr ex
64mm: 13d+2 cr ex
100mm: 22d+2 cr ex

Leaving the last two as 6dx2 and 6dx4, respectively, probably wouldn't break anything too badly (you're at roughly 90% of what the damage "should" be). The above is for TL 8; trend I suggested earlier for lower TL's.
__________________
GURPS Overhaul
Varyon is online now   Reply With Quote
Old 02-16-2020, 03:59 PM   #7
Michael Thayne
 
Michael Thayne's Avatar
 
Join Date: May 2010
Default Re: [High-Tech][Ultra-Tech] Ultra-Tech style write-ups of TL5-8 ammo

Quote:
Originally Posted by Varyon View Post
For explosives, they should really improve at every TL, as REF of contemporary explosives go up. Roughly speaking, and assuming REF is 2 at TL8, 1.5 at TL7, and 1 at TL6, you're looking at x0.85 to damage at TL 7, x0.7 damage at TL 6. Call the former -1 per 2d, the latter -1 per 1d. If you want to go lower, TL 5 is probably REF 0.5 (x0.5), TL 4 is REF 0.4 (x0.45), and TL 3 is REF 0.3 (x0.4), all of which would count as -2 per 1d.
This all strikes me as dubious. In WWI amatol was widely used and High-Tech lists its REF as 1.2. And while it's true that High-Tech has thermobaric explosives with REF 2 appearing at TL8, but not every TL8 warhead is thermobaric! Warhead designers don't just care about maximizing their TNT equivalent; finding stable and easy to handle mixtures is also quite important. I'd guess that in practice the common explosive mixtures used in shells and bombs at TL8 have an REF around 1.4, which is only going to give you 8% more damage than amatol.

Quote:
Fragmenting explosives "use up" some of their power producing and propelling fragments, so those designed to not produce fragmentation (like thin-shelled HEC rounds) should do more damage. Roughly speaking, fragmentation tends to be around 1d per 20mm (which matches up well with your values), and every 2d of fragmentation generated "costs" 1d of explosive damage.
In theory this is right but Ultra-Tech ignores this and I may too for the sake of simplicity. Of course you can try to be more realistic if you like.

Other thoughts: Ultra-Tech's TL9 stats for APHEX aren't that different from some of High-Tech's TL6 stats for APEX. Maybe they aren't that different, at least at the level of resolution GURPS cares about? Similarly TL8 and TL9 thermobaric don't seem that different, but I'm not totally certain about that. EFP I'm really uncertain what to do about because High-Tech only has one example.
Michael Thayne is offline   Reply With Quote
Old 02-16-2020, 06:08 PM   #8
Varyon
 
Join Date: Jun 2013
Default Re: [High-Tech][Ultra-Tech] Ultra-Tech style write-ups of TL5-8 ammo

Quote:
Originally Posted by Michael Thayne View Post
This all strikes me as dubious. In WWI amatol was widely used and High-Tech lists its REF as 1.2. And while it's true that High-Tech has thermobaric explosives with REF 2 appearing at TL8, but not every TL8 warhead is thermobaric! Warhead designers don't just care about maximizing their TNT equivalent; finding stable and easy to handle mixtures is also quite important. I'd guess that in practice the common explosive mixtures used in shells and bombs at TL8 have an REF around 1.4, which is only going to give you 8% more damage than amatol.
Looking at the table in High Tech, 2 struck me as an acceptable estimate for TL 8 warhead fillers, which range from REF 1.6 (LX14) to 2.3 (CL20). 1.5 seemed about right for TL 7, as they range from 1.3 (Pentolite) to 1.7 (Octogen); they most hover around 1.4, but I opted to round this up due to GURPS' rampant pentophilia. For TL 6, I just went with straight TNT, as it's mentioned in its text as being an extremely common warhead filler, and because it matched the general trend.

Note all of the above are stated to be "warhead filler" in the table; they are by definition stable enough to function in a warhead (although some are more usable than others, which is why I didn't just go with the most powerful warhead filler REF at each TL). Still, if you feel it's more appropriate to have TL 6-8 all use explosives of markedly similar REF for their explosive bullets, even if only for simplification, that's certainly workable. There's a lot of overlap, after all (REF 1.6 is achievable for warhead filler as early as TL 6, in the form of Hexogen).

Quote:
Originally Posted by Michael Thayne View Post
In theory this is right but Ultra-Tech ignores this and I may too for the sake of simplicity. Of course you can try to be more realistic if you like.
*checks* So it does. And, honestly, it's perfectly acceptable to have their explosive damage match if you simply assume HEC, being concerned with producing less fragmentation, uses less explosive.

Quote:
Originally Posted by Michael Thayne View Post
Other thoughts: Ultra-Tech's TL9 stats for APHEX aren't that different from some of High-Tech's TL6 stats for APEX. Maybe they aren't that different, at least at the level of resolution GURPS cares about?
APEX has the notable difference that its piercing damage is reduced to 70% normal, just like normal AP ammo. HT's APHEX (TL 7, HT170) functions just like UT's APHEX, although it leaves calculation of explosive damage up to the reader (it doesn't even give a guideline for how much explosive charge, although by comparison to APEX one can assume just south of 5% bullet mass). APHEX is the APHC equivalent of APEX. The explosive damage of APEX and APHEX are likely the same, however. If UT's APHEX tends toward comparable explosive damage as is seen in HT, that's honestly more likely to imply UT underestimating the explosive damage appropriate for TL 9. Whether you interpret that as meaning TL 9 APHEX should get a boost to its explosive damage or that TL 8 and 9 APHEX get comparable explosive damage is entirely up to you. For EFP and similar, I'd be strongly tempted to simply have the damage reduction of general explosive ammo when going from TL 9 to TL 8 be applied equally to the others; after all, all of the explosive rounds in UT see the same damage increase (+1/die) when TL goes above 9.
__________________
GURPS Overhaul
Varyon is online now   Reply With Quote
Old 02-16-2020, 07:42 PM   #9
Michael Thayne
 
Michael Thayne's Avatar
 
Join Date: May 2010
Default Re: [High-Tech][Ultra-Tech] Ultra-Tech style write-ups of TL5-8 ammo

Quote:
Originally Posted by Varyon View Post
Looking at the table in High Tech, 2 struck me as an acceptable estimate for TL 8 warhead fillers, which range from REF 1.6 (LX14) to 2.3 (CL20).
According to Wikipedia, "CL-20 has not yet been fielded in any production weapons system". And while some modern weapons do use LX14 or similar mixtures, lots of weapons fielded by the US military are still using Composition B.
Michael Thayne is offline   Reply With Quote
Old 02-16-2020, 08:28 PM   #10
Rupert
 
Rupert's Avatar
 
Join Date: Aug 2004
Location: Wellington, NZ
Default Re: [High-Tech][Ultra-Tech] Ultra-Tech style write-ups of TL5-8 ammo

Quote:
Originally Posted by Varyon View Post
UT's APEP is the equivalent of APDSDU. I'd suggest maintaining the HT options (and indeed allowing the enhanced penetrator option from UT to be split into the equivalents of APDU, APDSDU, and APDSFSDU would be appropriate). Personally, I favor the HT treatment (enhanced damage and lesser armor divisor, which works out to the same armor penetration).
I prefer higher armour penetration numbers to more damage. This has the same effect on penetration with less 'pink mist' effect on characters inside the armour.
__________________
Rupert Boleyn

"A pessimist is an optimist with a sense of history."
Rupert is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Fnords are Off
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 02:16 PM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2020, vBulletin Solutions, Inc.