I have been told that the fatigue of the spring can be corrected by simply keeping one less that a full load in the mag. This came from a gunsmith and a retired police officer. Your thoughts?
RL357Mag, Call a fellow by the name of Dave Koebensky at Wolff Gunsprings. Tell him what you've got, and see what he suggests. Over the years Dave has been a tremendous help to me; it's only rarely that he doesn't have a particular spring in stock. (Wolff Gunsprings is one of the largest firearm spring manufacturers on the planet!) Here's the number: 1.800.545.0077
Your other possible source is Numrich Corporation. 1.866.686.7424. Between these two companies you should be able to find most any gun part that you want.
You, probably, already know about this site; but, I thought I'd include it just the same:
Makarov Pistols