I give up. I just Google imaged a bunch of Smith & Wesson double action semi auto pistols of different model numbers, and a couple different models seem to have exactly the same construction as far as the trigger guard magazine release even the pattern of checkering on the grip. They look identical to what the OP posted.
Do y’all just not bother to read the posts? OP’s gun has already been ID’ed as a 4006. Why look at pics of checkering patterns when the OP’s gun has the model number clearly stamped on the left side of the frame?