No, saved hits had nothing to do with it - it was a fixed range weapon (0-20"/20-70" +1/+1 to hit S8
d10 wounds -6 armor penetration) and
if hit by enemy fire required the roll of
2d6. On an 11-12 you rolled on the Catastrophic Launch Chart. When rolling the scatter dice, if you rolled a misfire on the scatter range die and a hit on the direction die you also rolled on the
CL chart. The blast radius was 1/2" per missle in a fired salvo, up to 6" for the full load of 12 missiles launched. I found my 2E wargear book!
HBMC, you're right about it being 1:6 now that I remember. With sustained fire, each jam you rolled took a turn to remove; an assault cannon rolled 3d sustained and if you rolled all jams, you went boom. Unless you were a space marine dreadnought.
Edited for correctness!