I have the same build lined up in pieces here (7x57 M70), but with a #5 contour Lothar Walther, NECG sights, barrel mount sling swivel, and an exhibition black walnut blank.
The 7x57 fits just swell into a standard M70 action, as the feed rails are closely spaced on the M70, the bit of extra length makes no difference for feeding. I stagered 7x57 rounds in my mag, one right to the back of the mag, then one to the front, and so forth to a full mag. Got 100% feed reliability, and smooth as greased lightning. Also tried all rounds forward, all back, etc same results. With 175gr bullets especially, there actually isn't much wasted room in the mag. And you'd be able to seat way out too, giving a hefty boost to the 7x57.
I have also put dummies through mine over 100 times and came up with the same results. Feeds great!


















































