Nathan @ muzzle breaks and more and the Gentlemen that makes the Terminator breaks have the best setup to test the "theory" of loss prone or from a bench. Simple reason is they can control on the there test stands how much the gun move. Simply put they can make the gun so it cant move or consistently move freely a given distance.
Good point! I remember one of Nathan's test videos where he shot another round because of too much variation for his intended test goal, IIRC, it was greater than 20 FPS.