Just read John Zemanek's article in the May-June 1981 issue of Handloader magazine, "Effects of Crimping Handgun Ammo." Fascinating. It lets air out of many old-school ideas on the subject, namely that one particular type of crimp is always best for this or that ammo, this or that gun.

Of late, some of my cast bullet handloads for .38 and .357 revolvers have been less than stellar in regards accuracy, so I thought I'd try some variations on crimping. Bullets don't seem to be the problem. I've tried factory and they're no better. Switching powders and charges hasn't worked any miracles either.

I have the old standard rollcrimp in my dies, and I'd like to see what happens when I taper crimp the same ammo. The question is: which die?

Is it worth spending the extra money for a Lyman or RCBS or Redding when Lee sells a product at half or less? Talking strictly taper crimp here.

Interestingly, Zemanek found that in some loads, the profile crimp gave the poorest accuracy of all. His article is worth reading.

Look forward to your thoughts. Thanks.

I have Redding, RCBS and Lee taper crimp dies.

I've never found one to be superior to another.

In addition to 9mm and 45ACP, where a taper crimp is SOP, I have taper-crimped mild 38 and 44 loads. No issues with taper-crimped 9mm and 45ACP, but then, no opportunity to test against roll crimps.

With rimmed cartridges, taper crimps have caused occasional problems with bullet pull and that is totally unacceptable to me. Furthermore, since I could, and have compared roll and taper crimping in identical loads, I don't recall any instance where the taper was superior. My only motivation to taper crimp 38's and 44's was convenience...no need to trim brass. But the occasional, even rare, occurrence of a pulled bullet and cylinder lock-up is enough to make me happy to segregate the two types...taper for rimless, roll for rimmed.

That said, there's no substitute for finding out for yourself.

__________________
Carry.."hope" isn't a strategy

Sounds like a more serious problem if factory ammo won't shoot straight either. What distance are you shooting at? From a rest? Group size?

I use the Redding taper crimp on all of my light and medium 357 loads with plated and coated bullets. Full power loads must have a roll crimp.

I don't like the Lee crimp dies because they re-size the finished round which can reduce bullet diameter, at that's not a good thing.

Probably not the answer you want to hear, but to do it absolutely right, you may want to experiment not only with different crimp styles, but also the degree of crimp. Seldom is a "heavy" crimp needed for anything. I've found, even with factory equivalent .44 Magnum handloads, the lightest crimp that will keep the bullet in place under recoil will probably provide the best accuracy. As with everything else, however, there are exceptions.

John Zemanek didn't write a lot of articles or for very long before his death, but his handloading pieces contained far more useful information than those of any of his contemporaries. He did lots of testing, enough to provide very useful information to readers. I'd likely use Zemanek's suggestions as a starting point if your particular concern is addressed in the article. I'll have to re-read that one; been a long time since I've seen it. Good luck-

There are too many variables in obtainable accuracy to solely blame 'crimp' technique or style on the problem. But, as mentioned experimentation with the variables that you can control is in order. I have had 38 Special handguns that thrived with roll crimps and hated taper crimp. I have had the reverse also. I have never had a 357 M. that 'liked' taper crimp. The recoil and the powders used seem to demand a roll crimp. Applied properly, roll crimping has worked more often than the taper crimp for me.....at least in straight wall pistol cartridges.

An aside; If the best obtainable accuracy is your goal, IMHO you should purchase the best dies that you can afford. On the average, they will give you the best results. If you are a close range pie plate or beverage can shooter, the Lee dies will work. IMHO, you can do better with a little higher initial costs. ............

I have posted this link before in threads with a very similar subject line:

https://www.riflemagazine.com/magazi...d=212&magid=18


POWDER KEG

by Ross Seyfried

Crimps

The crimp, or lack of a crimp, is a very important component. Crimps can be: good, bad, indifferent, essential or just plain irrelevant. Handloaders who understand them and use them correctly are better at their trade and more apt to hit their targets.

Let’s begin with crimps we cannot live without and work our way through different kinds of loads and cartridges with varying degrees of "need."

Shotshells demand crimps, perfect crimps, to be at their best. Actually, crimping a shotshell is so essential that their value and quality are easy to overlook. Your first reaction to shotshell crimps is probably, "Well, sure, fool, you have to crimp them or the shot falls out." That is true, but there is more to it than meets the eye. We can and will make a full study of the art in another column, but for now we will look at the basic premise.

Beyond folding the shell closed so the shot does not roll around in our pocket (very embarrassing), the crimp quality has a huge impact on a shotshell’s ballistics. This is one arena where a handloader is hard pressed to be as effective as an ammunition factory. They get to start with brand new hulls, while we usually are working with second-hand models. Also, because we are frugal, we are apt to use a shotshell hull a bit too often. The essence of shotshell crimps is uniformity, tempered by strength. The "crimp-pull" on a shotshell is a bit like revving the engine before you release the clutch. The resistance of the crimp is an important component in the powder burn. Usually less crimp pull means less efficient acceleration. A crimp that is too shallow, or formed with a soft, worn hull is apt to cause low velocity and inefficiency. Conversely, a crimp that is too deep can actually cause excess pressure in an otherwise normal and correct load. The bottom line is that they should be the same from shell to shell, and they should be very similar in depth to factory shells with that hull type. Variations that cause velocity spread are simply apt to cause you to miss, while uniformly inadequate crimps can produce uniform velocities that are low enough to compromise the shell’s ability.

Handgun cartridges have a varying affinity for crimp, depending on the cartridge and load type. "Magnums," if loaded to full power, and/or ones that use slow powder, usually demand major crimps. Here the crimp has two functions: creating resistance to help the powder burn and to keep the bullets in the cases. Before we go further, it is important to understand that the actual "crimp," pressing the case into the bullet, is only part, perhaps a minor part, of the total called bullet pull. More important than the crimp itself is the grip the case walls have on the bullet. If you need a heavy crimp and the case does not grip sufficiently, no amount of mashing the case mouth into the bullet will make up for the shortfall. The most obvious demonstration of weak bullet pull is with big-bore, magnum revolvers. These machines are inertial bullet pullers. Under recoil, the gun and case move rearward violently, while the bullet wants to stand still. If, after firing part of the cylinder, the bullets are beginning to creep out of the unfired loads, the bullet pull was insufficient. Our first reaction and remedy is to apply more "crimp." Assuming the offending rounds had a good crimp to begin, the culprit is probably not the crimp at all. Instead, it is most likely the cases were not hugging the bullets tightly enough. At times sizing dies are undersize, but oversize expanders are far more common. Essentially, the "hole" in the case left after resizing and expanding should be .003 to .005 inch smaller than the bullet diameter. After you seat a bullet, you should be able to see and feel a slight bulge in the case at the base of the bullet.

Also, I think I have perfection if I can detect the location of the grease grooves in a cast bullet by very slight depressions in the case wall. This kind of load is doing everything it can to hold the bullet in place. This not only keeps the bullets from jumping out of revolver cartridges, but also from being driven into auto-pistol rounds during the feeding cycle. If you begin with this heavy case grip on the bullet and add a good crimp into the crimp groove or cannelure, the bullets should stay put. This holds true for even the most savage recoil produced by the heavy .45s, .475s and .500s. If you have this maximum bullet pull and the bullets still refuse to stay put for four or five rounds (depending on whether the gun is a five- or six-shooter), the trouble is likely due to too much powder compression. There is a limit to how much you can compress powder and keep the bullets in place. Once you cross that line, no amount of crimp and case tension can overcome it.

As we back away from the fire-breathing applications, crimp can become less important. Most auto-pistol rounds only want the slightest degree of roll or taper crimp to streamline the case mouth to increase feeding and ejection reliability. If the loads are of modest power and the powders are relatively fast (in contrast to H-110, W-296 and 2400 speeds), you might need little or no crimp at all. Experimentation is the answer. Check first for function and ill-fated jumping bullets. If everything works okay, compare the accuracy and velocity spread of heavily crimped versus lightly or uncrimped loads. The .32 H&R Magnum is an interesting example. Even when loaded with "heavy" 110- and 120-grain bullets, driven by H-110 powder, uncrimped rounds are usually slightly faster and offer groups half the size of heavily crimped ones.

Whatever degree of crimp you use, it is always best to apply it with a separate operation, first seating the bullets to correct depth and then crimping with a separate die or the standard seating die with the seating stem backed away from the bullet. In contrast to shotguns and handguns where crimp is usually a good thing, rifles often do not like crimp, nor do they need it.

I am fascinated by the ammunition factory’s desire to almost cut the bullets in two with the crimp on almost every cartridge they make - including recoilless things like .222 Remington and .22 Hornet. In my opinion crimp is either neutral or harmful to accuracy and rarely offers any benefit at all. Very heavy cartridges, like the .458 Winchester, might try to drive the bullets into the cases during recoil. Normally, good heavy case tension, as prescribed for handguns, will prevent the disease. If not, a slight crimp might help. Also, semiautomatics might need a bit of crimp to keep the bullets in place while the action slams and batters them into the barrel, and lever actions with long, tubular magazines might want some crimp. Beyond applications that absolutely demand it, crimping bullets in rifle cartridges is frivolous at best.

Ultimately look at crimp on metallic cartridges as secondary to the resistance of the case neck itself. Apply maximum crimp to heavy handgun loads and then work from the premise that crimping most other cartridges is unnecessary.

Ditto what Doubless said.

If you've got decent case neck tension, "friction fit" as Seyfried says, you don't really need any crimp at all for relatively light loads. For most loads I use the regular RCBS roll crimp die set to "no crimp." This just removes the flare, enough so that the round goes in and out of the chamber easily.

I do have the Lee Taper Crimp die, and it works just fine but doesn't seem to add any accuracy to that achieved by the "no crimp" method described above, so it just sits on the shelf unused, next to its big brother for .44s. But they are real cheap, so go ahead and get one and try it. You might like it.

For heavy loads and/or real light guns, you do need a roll crimp to prevent "bullet jump" or "creep."

As far as the Lee Factory Crimp Die (FCD) goes, no comment.

__________________
USAF, 69-92
Vietnam, 72-73

Redding has a micrometer adjustable taper crimp die that is perfect for fine tuning to different headstamp/thickness of brass. Work great on all of my 45 ACP loads but I am not sure if available for all calibers.

The Zemanek article the OP mentions is actually in Handloader #151 which is the June 1991 issue.
You can read the article at:
https://www.riflemagazine.com//magaz...151partial.pdf
The print issue is sold out.
Luckily I have the Wolfe magazine index and found it in there.
https://www.riflemagazine.com///cata...m?ProductID=30

I use the Redding 44 taper crimp die when loading bullets with no cannelure or crimp groove.
Sometimes I load a bullet so the case and the cannelure or groove don't line up.
These also get a taper crimp.
In the single shot Encore I mostly use the taper crimp to iron the bell mouth out.
Some slower powders like A1680 do like a good crimp to burn correctly in cylindrical brass.
I have had a couple of those go WHOOSH instead of bang.

__________________
NEMO
"Everything 44"

I started using the REDDING profile crimp dies a few years back when I was loading .45 Colt loads for my Freedom Arms M-83 revolver. It applied a consistent crimp that gave me more consistent shot to shot velocities than the old RCBS dies gave me.

For that particular situation crimp did make a difference.

Thanks for posting the links Nemo.

The Redding Profile crimp is generally recognized as the best "roll" crimp there is.
It has come in #1 in a couple of bullet retention tests.
I use it whenever I can.

__________________
NEMO
"Everything 44"