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Old 11-10-2010, 06:06 AM
Steve C Steve C is offline
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A roll crimp tool rolls the top of case mouth into the bullet usually into a crimping groove or cannelure and is used for revolvers where the case does not head space on the mouth of the case. The first picture below shows a close up of a .357 mag with a roll crimp.



A taper crimp squeezes the ends of the case mouth inward along the side of the bullet but does not turn the case mouth in. The picture below shows an example of a .45 ACP case with a taper crimp. Notice the shiny ring just below the case mouth where the dies has worked the brass and pushed the sides of the case evenly against the bullet. The constriction of the case is narrower at the top of the case mouth than below it.

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