If you compare the picture of the OP's rifle with the one in the advertisement, not the position of the rear sight. The OP's sight is on the barrel while the one in the ad is on the breech. I have a few M50s and only one was a .270. It had a deep cut in the top of the breech for the rear sight. This bothered me for two reasons. One it looked funny like maybe somebody screwed up plus the fact that I was not all that comfortable with rough 60KPIS that close to my face and a thin spot right where the highest pressures would be. That rifle is not a 7x57 BTW. They must have made a change to the style on the OP's rifle fairly quickly and I haven't seen one with the dovetail over the breech since that .270.
I've owned a few of the pre-64 M70s and frankly, I'd take the J.C. Higgins M50/51 over the M70 any day and twice on Sunday.
Paul B.

Our forefathers did not politely protest the British.They did not vote them out of office, nor did they impeach the king,march on the capitol or ask permission for their rights. ----------------They just shot them.
MOLON LABE