When I hear "stovepipe" in the context of an older gun in new hands, I think sticky extractor.
If the extractor is sticky, the chance of stovepipes goes up.
Drown the extractor real good in Break-Free CLP.
Make sure there is no goo stuck under the claw.
While you're at it, pull the selector and the firing pin.
See
Model 39's at AIM - which "European police" dept?
Hose out the mag-disconnect plunger.
Blow the excess CLP out of the cracks and crannies.
Get back out there and re-test.
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