My point about the bell is that if you see a pronounced "bell", the resizing die is opening the case too much - there shouldn't be a visible bell on a 9mm - just look straight-sided. A lot of people don't realize the case is tapered normally - its not straight sided (and one of the reasons why you see powder burns frequently around the case mouth of 9mm - flashback on the mouth as it begins to move back in the chamber). I find 9mm a pain to reload because of the taper. In my turret press its a nuisance to resize - takes too much pressure. I decap 9mm (well, all my calibres, actually) in a Lee hand press with the resizer, because it applies more force and is faster. The rest I decap with the universal decapper, into the tumbler, and then turret loading goes quite quickly.
To help Skhunter understand roll vs taper crimping - have a look down into the chamber of the 9mm - you'll see a tiny "rim" down in the chamber. Its this "rim" that the case mouth must properly butt up against for proper headspacing of a rimless cartridge. If the case mouth is "rolled" like is done for a revolver cartridge, the case mouth could actually ride past the "rim", resulted in the cartridge more deeply seated in the chamber than designed, resulting in a potentially dangerous overpressure condition. Taper crimping is intended to hold the bullet and restore the case mouth to proper geometry for the chamber. This why the case mouth on rimless cartridges must be treated with respect. If they're overworked in the press they eventually become brittle and may fail when the cartridge is slammed home by the slide. Not good.
Roll crimping is done to hold the bullets from creeping forward under the inertial shock of the gun firing, since revolver chambers and magazines are one and the same. The roll actually bites the bullet and many revolver bullets have a cannelure (indented ring) for the purpose. Think inertial hammer - that what happens to your bullets in a revolver cylinder if there's nothing to hold them back.
To help Skhunter understand roll vs taper crimping - have a look down into the chamber of the 9mm - you'll see a tiny "rim" down in the chamber. Its this "rim" that the case mouth must properly butt up against for proper headspacing of a rimless cartridge. If the case mouth is "rolled" like is done for a revolver cartridge, the case mouth could actually ride past the "rim", resulted in the cartridge more deeply seated in the chamber than designed, resulting in a potentially dangerous overpressure condition. Taper crimping is intended to hold the bullet and restore the case mouth to proper geometry for the chamber. This why the case mouth on rimless cartridges must be treated with respect. If they're overworked in the press they eventually become brittle and may fail when the cartridge is slammed home by the slide. Not good.
Roll crimping is done to hold the bullets from creeping forward under the inertial shock of the gun firing, since revolver chambers and magazines are one and the same. The roll actually bites the bullet and many revolver bullets have a cannelure (indented ring) for the purpose. Think inertial hammer - that what happens to your bullets in a revolver cylinder if there's nothing to hold them back.
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