Handloading ammo for your favorite handgun shouldn’t be difficult, but you should never skimp on the crimping process.
What to know about crimping:
- At the most basic there are two types of crimps: roll crimp and taper crimp.
- A roll crimp is when the mouth of the case is rolled into the bullet’s cannelure.
- A taper crimp is where the sidewalls are squeezed against the bullet to secure things.
- Roll crimping is used on most magnum revolver loads — those bullets with a cannelure.
- Taper crimping is preferred for most autoloading pistol cartridges.
- A third method, the “combo crimp” is another option.
Handgun cases generally aren’t a difficult prospect to load for, but the crimping process might require some additional attention in order to keep things as consistent as possible.
There are, generally, two types of crimps:
- 1. Roll crimp: Where the mouth of the case is physically rolled into the bullet’s cannelure
- 2. Taper crimp: Where the case mouth is left alone and the sidewalls are squeezed against the bullet to keep things in place
Roll With It
Revolver loads using a bullet with a cannelure utilize the roll crimp. The true hard-kicking magnum cases, such as the .44 Rem. Mag., the .454 Casull and the .500 S&W, will easily cause a bullet to slip forward out of the case mouth. This bullet slip — also referred to as pulling crimp — can and will cause your cylinder to lock up tighter than a drum, and the fix is not easy. So, I make sure to put a nice, heavy roll crimp on all my revolver cartridges.
The process is rather simple and uses the seater die to apply the crimp. What I do, while setting up my dies, is to make several dummy cartridges to get the crimp and seating depth perfect before I start loading cartridges. Inside the seating die, at the very top of the die, is a small shelf that rolls the case mouth toward the center point of the case. It takes some experimentation — and several ruined cases — to find the proper amount of crimp by adjusting the seating die body up and down until you get it right.
Once you do find it, and lock the die body down in the press, you’ll be all set — that is, until you switch bullets. A different bullet will most likely have a slightly different seating depth, and you’ll have to adjust the seater itself until you get the cannelure centered perfectly on the case mouth.
Roll crimping works best if you keep all your brass trimmed to the same uniform length. If your brass isn’t uniform, the short cases won’t have enough crimp, and the long cases will have too much crimp, bulging the case and making for feeding problems in the cylinder. I like to trim all my cases to the SAAMI-specified length, or just slightly shorter (I’ve had a few runs of brass that actually came short from the factory), so as to keep it all neat, tidy and uniform.
Taming The Taper
Taper crimping is the preferred crimping method for the autoloading pistol cartridges and for revolver cases using bullets with no cannelure. A separate crimping die is employed, which will squeeze the case walls tightly against the shank of the bullet.
Because almost all of our popular rimless pistol cases — think 9mm Luger, .40 S&W and .45 ACP — use a good, square case mouth for headspacing, a roll crimp wouldn’t be a good idea, and the taper crimp is more than adequate to keep the bullets where you seat them during the violent cycling of the action.
Applying any roll crimping to a cartridge that headspaces off the case mouth will definitely affect the case length, and it will create possible headspace issues, including errant velocities. The taper crimp method also works for the wheelguns, either in lieu of a roll crimp — again, for bullets with no cannelure — or in conjunction with a roll crimp, to further keep things in order and in place.
I’m a huge fan of the Redding Micro-Adjustable Taper Crimp dies because they’re furnished with a micrometer adjustment at the top of the die to allow the loader to precisely adjust the amount of crimp applied to the cartridges. It’s especially handy if you use a progressive press because you can quickly and accurately adjust the crimp should you switch brands of brass and find you require more or less. These dies allow for more precise adjustment, using the micrometer in lieu of adjustment via the die body, which relies on the pitch of the threads and that can introduce a bit of unnecessary slop into the mix.
The ‘Combo’ Crimp
There’s a third method, a combination of the two types, designed for use with those cartridges that don’t headspace off the case mouth. The Redding Profile Crimp Dies combine the roll crimp and taper crimp for the ultimate in uniform crimping. These dies require the bullet to be seated first — and they must be seated to very tight tolerances in order to achieve the best consistent results — and the crimping is done in a secondary phase.
The cases then have both a roll crimp and taper crimp applied, giving extremely uniform results. I’ve used this method for making ammunition for the .44 Rem. Mag., .38 Special and .357 Mag., and I’ve noticed a marked improvement in accuracy and uniform velocities throughout.
Don’t get too crazy with the amount of crimp you apply; a light profile crimp will hold things nice and tight while not overworking your cases. The Profile Crimp dies might take a bit of getting used to, but once you’ve got things adjusted properly, you might find yourself wondering how you ever lived without them. These dies can help wring the most accuracy out of an already solid target pistol.
They are also available with a micrometer adjustment, as the Micro-Adjustable Profile Crimp die, giving the same precise adjustment that the Micro-Adjustable Taper Crimp dies do. As a side note, Redding produces these crimp dies for many of the popular straight-walled rifle cases, such as the .45-70 Govt. and .458 Win. Mag., and many of the older black-powder-era cartridges like the .38-40 Win. and .32-20 Win.
Your crimp is a key part of the handgun ammo equation and can easily even out your velocities and tighten up your group sizes. After all, that’s a huge part of the reason we handload in the first place. A little bit of extra attention to the crimp will go a long way toward producing the best ammunition available.
Editor’s Note: This “Reloading Bench” column is an excerpt from the September 2017 issue of Gun Digest the Magazine.
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