By Duane Thomas
Polymer-coated bullets have become quite popular among handloaders, since they’re generally less-expensive that jacketed bullets, and avoid any of the negative issues than can attend firing bare lead bullets. However, loading coated bullets does require a bit of attention to detail, especially when adjusting the case mouth expansion die.
An important part of handloading is adjusting the die that flares the case mouth to accept the bullet. There are a lot of similarities between loading coated bullets and plated bullets. In both cases, one reason the bullets are so inexpensive is they’re made of extremely soft lead wire, then a protective material is applied over the bullet to avoid barrel leading, and prevent vaporization of bare lead as it travels down the bore producing the clouds of gray smoke we associate with firing bare lead bullets. Since that lead-laden smoke can, depending on lighting conditions, occlude a clear view of targets in a match situation, also it’s a source of potential lead poisoning with repeated, long-term exposure, keeping it to a minimum is obviously desirable.
As a general rule we want to avoid over-flaring the case mouth, since this works the material really hard. The necessary expansion of the case mouth during flaring, then being compressed back down at the crimp station, if done time after time, over multiple loadings, can eventually cause the material to weaken so much the case mouth will split as a bullet is forced down into the casing, at the seating station of the loading machine. The harder we work the case mouth, i.e. the greater the case flare, the sooner the case mouth will split. So, we want to keep case mouth flare as minimal as possible.
The problem is, with coated bullets, the coating is fairly thick. Also, compared to jacketed or even plated bullets, it’s soft. The minimal amount of case mouth flare that would work perfectly with jacketed bullets will cause the soft polymer used in coated bullets to “smear” up and over the case mouth as the bullet is driven into the casing at the seating station. Even after crimping, you’ll wind up with a “blob” of material pushed over the case mouth around the bullet where it enters the case mouth that can easily prevent cartridges from feeding into an autopistol’s chamber, or even when attempting to insert cartridges into a revolver’s cylinder.
The only way to avoid this is to flare the casing more than would be necessary were you loading bullets with a harder/thinner protective layer. With coated bullets, we still don’t want to work the case mouth during flaring any more than necessary; however, in this case “what’s necessary” equals “quite a bit.”
Yes, applying a higher degree of flare to case mouths means that, when we handload coated bullets, our casings aren’t going to last as long as when we’re using bullets that don’t require nearly as much flare, but this something with which we have to live if we want to load coated bullets.
