My recently acquired prewar(39) M70 .300H&H will cycle perfectly all rounds from a fully loaded magazine but when loading singly(gun range) it fails to feed app. 25% of the time. The cartridge is not as deep in the magazine as I think it should be but the follower friction "USUALLY" resists enough to allow the extractor to pop over the rim. Like my Classic Stainless 7mmRM, the feed rails are straight as opposed to my custom M98(.338-06) and Husqvarna commercial sporter(30-06) which have beveled feed rails. Is this situation common and are the feed rails straight on these pre war's? Would a stronger mag spring help?

You need a new heavier follower spring I believe.

I had a similar problem with my '06 -- a new spring from Gun Parts (www.e-gunparts.com) fixed it right up. Guess 63 years was about all it had in it...