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I use only three dies for pistol rounds.
Until I read this thread, it never even occurred to me that anything else was possible (just like it never occurred to me to try being gay).
Quote:
Originally Posted by markm
Seriously, it works well (3 dies, not gay sex). I've cranked out tens of thousands of rounds of .40S&W, .380ACP, and .30Carbine without incident.
I use 4 die sets, especially with plated bullets.
For me, personally, I think the type or amount of crimp is the last thing affecting my accuracy with a pistol. :-P
Tom, roll crimping and taper crimping is more about reliability, but doing either wrong can impact accuracy. Roll crimping revolver cartridges prevents the bullets from moving forward in the cylinder due to recoil when another cartridge is fired. Without a roll crimp, heavy recoil can cause a bullet to move so far forward that it prevents the cylinder from firing. The roll crimp also has the added benefit with slower burning powders of ensuring that more consistent pressures are reached before the bullet begins moving.
Taper crimps are used when reloading semiauto cartridges. The term taper crimp is really a misnomer because it's not really a crimp at all as it doesn't help hold the bullet in place. The point of taper crimping a cartridge is simply to remove the remaining flare that's left from the belling step. If this remaining flare is not removed, then feed reliability problems can result. Also, in extreme cases, headspace can also be impacted since semiauto pistol cartridges in theory headspace on the case mouth (reality is that they often headspace on the extractor, but that's another story). The amount of taper crimp that needs to be applied is simply enough to remove the remaining flare. Not enough and the remaining flare can cause feed reliability problems. Too much and you're just crushing the cartridge which can decrease the diameter of the bullet and actually decrease the tension between the bullet and case. You can't apply extra taper crimp in order to help hold a bullet in place. If you read or someone tells to you apply a "light" or "heavy" taper crimp, then they don't know what they're talking about. The correct amount is just enough to remove the remaining flare, that's it. Reloaders of semiauto pistol cartridges sometimes make a mistake when having problems with bullet setback. Bullet setback happens the bullet is pushed back in to the case during the process of the cartridge feeding in to the chamber. They sometimes incorrectly think that adding more taper crimp will solve their problem. Reality is that their problem is due to the case wall and bullet not having enough tension between them. Either the case isn't being sized down enough or the bullet diameter is not enough or a combination of the two. The correct solution is to size the cases down more (which often requires getting a new sizing die or fixing the one in question) or getting bullets that have a slightly larger diameter (if they're actually undersized).
All this to say that while we can take crimping of pistol cartridges for granted when it comes to accuracy, it's still important when it comes to reliability.
Bret is dead right.
^^Absolutely.