Fred M.
Yes, I have read the info on your site. I know you have done a bunch of work with the Handi's. And, maybe it worked for you, I have not tried everything you mentioned and will not argue with your results. But, #1, I am not trying to make a bench rifle out of this, I know what those are. #2, I am not trying to make 400 yard hunting shots with it either, in fact I only shoot at the range and then at paper. Just trying to make it shoot a good as I think it is capable of. Trying to make it shoot good is what I enjoy, different strokes you know. I have an idea that I am going to try and if it works I will post it here, but for now I won't discuss it. I think these rifles will shoot very good if you approach them right. Resting the forend on a bag, no matter what you do to the forend is not the way to go, in my opinion. BTW, have you tried using silicone between the forend and the barrel instead of the foam? If I could figure out how to keep silly putty between the forend and the barrel I would try that. I think silicone with very light screw tension has more potential than foam. If you have tried it let us know.
P.S. As to the harmonics, I think you are flat wrong on your statement, you will have barrel harmonics any time a bullet goes down the barrel, period. Don't make any difference how it is supported. Also, what differnece does it make about pressure on the latch as long as it stays locked up.