Wording for this is confusing:
<i>When resupplying ammunition, the grenade launcher selects any combination of grenades whose levels do not exceed that of the grenade launcher + 2.</i >
my calculations for a level 8 mech grenade launcher, any combination of grenades would not be able to exceed 8 + 2 = 10. To me, that would be 10 level 1 grenades, or 5 level 2 grenades, or 3 level 3 grenades, 2 level 4/5 grenades, or just one level 6/7/8/9/10 grenade.
But then it gives examples which seem to contradict this statement:
<i>For example, a mech with an 8th-level grenade launcher could carry five mk 3 frag grenades (level 8) and four mk 2 cryo grenades (level 10)....</i>
Wouldn’t 5 mk 3 frag grenades (level 8) be 5x8=40 which far exceeds the 10 calculated above. And four mk 2 cryo (level 5) would be 4 x 5 = 20, which again exceeds the 10 calculation above?
Anyway, the wording seems odd and I am confused.
No individual grenade can have a level higher than that of the grenade launcher's level +2. The total level of all the grenades is completely irrelevant. I think the main sentence could be a little clearer, but the example demonstrates what they actually mean.
There's still the question of what the save DC for a mech's grenade is though.
The DC should be 10 + half the grenade’s item level + the mech's Dexterity modifier? Any penalties the mech takes to their attack rolls also applies to this save DC.