Trying to find information here. I have a this shotgun, cut down (machined, chill) to 18 5/8". I would LOVE to add a red dot to her for some .780" round ball hard cast hotness. Has anyone had experience adding a rail or something to these? Obv not around the breach / chamber area, but where can I SAFELY drill / tap for a rail / optics mount? These barrels are BEEEEEEEEEFY, so I would assume somewhere maybe out close to the forearm screw would be safe as far as pressure goes?