I recived an email from Michael: "I have had a look at the posts on the website, and I think John (Chingford) has hit the mark. Your coin is F.325. This has my reverse K*, and the constant and most obvious feature distinguishing it from reverse M is the wide date. On reverse M it is much narrower. There are other features, as you know, but, as with the comparable penny reverses, this is the most obvious and easiest way to tell. As for the weight, your coin equates to 91.28 grains, which is fractionally above the range given by Peck for the Bun Head halfpennies (max. 90.8g). Although flans will vary, and yours may be possibly a fraction thicker than most, I think it is the COLLAR which you have measured, rather than the flan (planchet). To measure the latter, you would need calipers. I recollect that I had specimens of F.325 with a wide COLLAR, overlapping the surfaces, and I think your coin is one of these." I am still happy with a "F.325 a wide COLLAR" variety outcome. Next step measure the flan using digital callipers purchased from Chris.