You have stated that the barrel is only 21.5 inches well it looks like from the picturea and the data we have that for some reason the barrel was shortend from the breach as the sight seems to be back 1/2 of a inch. how far from the muzzel is the front of the rear site with that measurement and then measure fromt the front of the reat sight to where the bolt face is when closed this may help answer a few questions and raise a few more.