OK but came yesterday.......I had emailed the vendor and expressed those concerns about it collapsing they assured me that would not happen and if it did send it back....?so today I rebarreled one of my model 12 actions that I had laying around with a varmint contour 26 inch 22-250......I took a digital mic and took all measurements od i,d, threads and length and width and flats....put a tight wrench on it tightened it to 80 psi on purpose.......shot it and after 22 shots marked the bbl where it was headspaced loosened it removed the barrel and then reinstalled it NO PROBLEM. Headspace was spot on Fired 12 more rounds and grouped the same.....?I like this bbl nut I am going to order more