I know from the CRB p. 183 that Grenade DC is
DC = 10 + 1/2 Grenade item level + attacker Dex Mod (ignoring penalties).
But looking through Alien Archive example NPCs the Grenade DCs are all over the board, and don't seem to be related to that formula. I thought then they must be related to the Ability DCs listed in tables 1, 3, and 5. But they don't seem to be related to those, in any way I can determine.
For example take the Nuar Specialist on p.86 of AA. It has a frag grenade III DC of 18.
A frag grenade III is item level of 8. The Dex mod is +0 The CRB would have
DC = 10 + 1/2 8 + 0 = 14
Table 3 for Experts of CR 8 have Ability DC of 18.
Ok, I thought, just use the Ability DC for Grenades. But that doesn't seem to hold.
Aeon Guard (CR 3) p. 6 of AA
Grenade DC of 14, regardless of Grenade level. But Table 1 has Ability DC of 12. The NPC has a Dex mod of +4, so that can't be it.
How does one determine the Grenade DCs for NPCs?