Jeez, how hard is it to say, "Gosh, I'm terribly sorry. I've had a major business interruption due to flooding. I've had only intermittent and limited internet access and no voicemail access, and I haven't had the time to go through all my various emails, and I simply missed this issue. I understand the concern, and will reach out privately. Rest assured, the OP will either have the gun or a refund of his money (his choice), and on terms that leave him happy. Because that's what is important to me and my business - happy customers. For everyone who offered kind words in my defense, you have my thanks."
Or something like that. I know the "grumpy gunsmith" is kind of a well-worn trope, but, come on, swallow a little pride and apologize.