I recently acquired a Remington manufactured '17 with a 9-18 barrel date from a military retiree who had gotten through CMP, supposedly via Denmark. The rifle isn't a rework and is still has 90% of its original blue finish but there is a nicely machined rounded notch at the rear center of the receiver ring. I've heard all kinds of explanations for the notch but after a little experimentation I have a plausible explanation: Using USGI M2 Ball ammo in Springfield stripper clips, when inserting these in to the Enfield action, there are no guide recesses as with the '03 or '03A3 Springfields, and the loaded clip cants forward, barely clearing the receiver ring. This isn't much of a problem with bare hands but attempting to load stripper clips with heavy gloves makes it more difficult to have the bullet tips clear the receiver ring. Basically, the notch facilitates rapid loading with gloved hands. Considering that these rifles were supposed to have been used in the cold climates of Canada, Norway and Denmark, this is as good an explanation for the presence of the notch as I can find.