I'm pretty sure it already does this. I can't think of any examples where the gun doesn't render over things. The only difference is with T3D it pushes the weapon back as you get close to a wall. I haven't tested it, but I believe the only code doing this is this:
https://github.com/GarageGames/Torque3D ... 2155-L2189
Be advised though, that removing that bit will let you shoot through a wall. Once you move the muzzle into the wall the muzzle starting point will be past the wall and your bullet will start after the wall. I think this can be avoided by just approaching the problem from here:
https://github.com/GarageGames/Torque3D ... 1807-L1811
As far as I can tell removing that bit would prevent the rendered muzzle vector from being corrected for collision, but still leave the actual muzzle vector corrected. There is a chance drawing the weapon is depth tested ( I didn't look ), resulting in the weapon being clipped by the wall you're walking into, this can be avoid by turning off depth testing in the stateblock for the shape image.