Winds to Pre-tension Romanian AK Drum?

My brother likes to take things appart. He took apart his Romanian AK 75-round drum losing the pre-tension on the spring. Does anyone know how many winds should be put on the spring to give the proper starting tension?

I plan on digging out my drum, pulling the cover to see if I can get a count on the number of winds when empty, but would still be interested to hear if anyone knows the number off-hand, or it you know of a site (or have a description) which might help him as he re-assembles and tensions the spring.

Thanks in advance for any answers.

--Joe

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"Strength is the outcome of need; security sets a premium on feebleness." -- H.G. Wells (The Time Machine)