I have been surfing a bit on thr "DPT" issue after looking at the gunbroker post. I found a couple of refrences to the "DPT" mark on no 2 MK IVs. Could the DPT mean Drill Purpose Trainer? It makes sence to me that a DP rifle would be perfectly suitable for use in a .22 conversion. The economics of conversin to trainer vs. DP seems logical to me.