Why does my shotgun destroy buildings?

[doc. caliban 34]

I'm working on a shotgun mod that has custom buckshot and an explosive round that emulates the FRAG12.

 

The problem I'm seeing is that they both destroy destructible buildings, which makes no sense.  The frag round only does a tiny fraction of what a vanilla 40mm does and shouldn't be destroying buildings either.  Something in my config must be wrong, and I was trying to keep the damage toned down to realistic levels as well.

 

One factor I have a hard time with is "caliber" where 1 is supposedly the penetration of a 7.62mm round.  I'm not so much worried about my specs in general though.  I really need to end up with double-ought that doesn't take a control tower down after a couple dozen shots.  lol

 

Any feedback about the config at all is welcome though.

 

Here's what I've got:
 

class CfgAmmo
{
    class SubmunitionBase;
    class ShotgunBase;
    class BulletBase;

    class B_12Gauge_00Buck: ShotgunBase
    {
        simulation="shotSpread";
        hit=2;
        indirectHit=0;
        indirectHitRange=0;
        cartridge="FxCartridge_65_caseless";
        cost=2;
        typicalSpeed=404;
        visibleFire=4;
        audibleFire=8;
        airFriction=-0.008;
        caliber=0.3;
    };
    class B_12Gauge_FRAG12: BulletBase
    {
        hit=42;
        indirectHit=1;
        indirectHitRange=1;
        suppressionRadiusHit=5;
        explosive=0.02;
        caliber=0.3;
        typicalSpeed=274.3;
        airFriction=-0.008;
        cartridge="FxCartridge_65_caseless";
        deflecting=3;
    };
};