Che cosa è l'effetto clessidra del 9x21 #short
The hourglass effect in 9x21mm cartridges is an aesthetic defect caused by excessive case tightening relative to the bullet. While visually unappealing, it typically doesn't impact function. However, attempting to eliminate it by reducing radial neck tension can lead to bullet setback during cycling, potentially causing firearm malfunctions like failures to chamber.









