To begin, order a replacement magazine spring for the Makarov pistol from Wolff Gun Springs (http://www.gunsprings.com) "MAKAROV 9mm +10% XP MAGAZINE SPRING Part #78871" for a single spring (#78873 = 3 pack; #78874 = 10 pack).
When you receive the Makarov spring you'll immediately notice that it is longer and much stronger than the P-64 spring. The bottom spring coil configuration is different and the coils are wound in the opposite direction. However, both springs are made of .039" (1mm) diameter wire. And, because the Makarov replacement spring is made to work with the 9x18mm Makarov cartridge, it can be easily modified to fit into the P-64's magazine.
Below is a photo of the original and modified springs. The one the left is a new, unmodified, Makarov replacement spring. The center spring is a modified Makarov spring that has been installed in a fully loaded and well used magazine for more than a year. The original P-64 spring is on the right.
To make the modification, set the new Makarov spring next to the P-64 spring with the angled top "follower" coil of both springs facing in the same direction and compare them. You'll notice that the Makarov spring has 17 coils and the P-64 spring has 16. Now, count off 15 coils on the Makarov spring and, using a good pair of diagonal wire cutters or Dremel type cut-off tool, cut off the remainder of the Makarov spring making sure to leave the straight section of the last coil as long as possible. (Yes, FIFTEEN coils! Believe me, if you cut the replacement spring so that it has the same number of coils as the original P-64 spring it will be too strong and you will likely experience feeding problems.) Make sure to orient the new spring correctly before cutting (the reverse spring coil winding does make it a bit confusing). You must cut the last coil with the topmost "follower" coil slanted upwards and facing towards the front so that the straight cut-off segment of the bottom coil ends up on the RIGHT side in order to be able to form the spring "tang" for locking the P-64 magazine base plate.
Now take a pair of vise-grips and clamp it onto that straight section exactly where the bend must be made to create the tang. Take another pair of pliers and bend the end of the wire outwards 90 degrees. Using the diagonal cutters or cut-off tool, cut the tang to the same height as the original one on the P-64 spring and dress down the sharp edge created by the cut with a file or stone.
That's all there is to it! You can now assemble the magazine. Because the Wolff replacement is an "extra power" spring, and therefore much stronger than the original P-64 spring, I suggest when performing the initial assembly that you gently clamp the magazine in a soft jawed vise or "C" clamp to hold it vertical in order to use both hands to insert the spring and base plate. Also, after it is assembled, I would suggest fully loading the magazine and letting it sit at least overnight to remove the initial spring tension.
Good luck,
HD77
