[Varyon]

Originally Posted by Michael Thayne

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).

Originally Posted by Michael Thayne

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.

Originally Posted by Michael Thayne

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.