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This has a 30 degree crown, meaning the tip of the barrel is cut in a way that protects the top, thus providing better accuracy. The tip of any barrel should always be kept clean and protected from damage. Damage to the crown can lead to poor accuracy and precision. The shaping of the point on a muzzle where the end of the bore intersects with the face of the end of the barrel

Dillan, it is a profile designed into the end/exit of a barrel that is angled to cause even dispersion of escaping gases so the auctal bullet leaves the barrel with the most stability for best accuracy. youtube.com/watch?v=oGLwk19HH_g

Dillan, That is the machining on the barrel opening (crown) to ensure even gas expelling from barrel when fired for improved accuracy.

That is referring to how the end of the barrel aka the barrel crown is finished. The end of the barrel is cut at an inward slope of 30 degrees, you can make it out pretty well in this picture (picture is of 9mm not a 45, not much difference): gunsamerica.com/UserImages/3054/941886330/wm_13159210.jpg