Thanks for your reply Juglansregia, I have a No1 Mk111 mag which has the insert fitted for me to copy, if it looks like its to much of a problem, which by your reply it possibly will be, then I will just stick to the
fish belly and the Parker Hale style that I now make, I have a friend that has a 375 Lee Speed to test the
magazine out on, but as you have said not all of the receivers will be the same, which is a problem when the mags could go any where and nothing worse if they don't feed properly.