Off board arty and obstacles

[Stejones82]

Can anyone please refresh my memory or tell me where to look in the "user" or "sqb" files to find the discussion regarding support fires (off board support) and the incidence of clearing obstacles such as wire?

I know I have seen this occur, and seem to recall that there is a minimum caliber requirement (150mm?) but can't seem to find the rules.

In my Winter War tourney scenario, I dropped Russian 122mm on wire and it did not clear. Is the round too small? Is there a percentage chance?

Any info would be appreciated, thanks gents!

Steve