roll crimp vs. taper crimp

richrd · Mar 15, 2023

I'm working a target / plinking load for a .41mag but I think this would apply to .44's as well.

I can do a roll crimp with the seating die or I have a taper die,

from an accuracy stand point, is one better than the other?

thanks
Rich

tominboise · Mar 15, 2023

Only way to tell for sure would be to load the same components and crimp some both ways, then shoot them to see.

But from my experience, no. I roll crimp all revolver rounds, except 45 ACP. I taper crimp the 45's because that's how my dies are set up for my 1911.

rockquarry · Mar 15, 2023

Many like to argue the topic, some without ever having done any testing to see what works better. My suggestions apply to cast bullets but may work fine for jacketed as well. Try both crimp methods and shoot some groups at 25 yds. from a good benchrested position using proper equipment.

When you crimp, regardless of the crimp type, crimp just enough to prevent any bullet movement under recoil and no more. Many crimp way too much, some with the belief that heavy crimps make powder burn better. This may be true in some instances; I've never seen it. However, as part of your testing, try some heavier crimps and record the results. If you have an interest in accuracy, you can't experiment too much. Don't dwell on ES and SD numbers; these are indicators of consistency only, not accuracy. Many, many, more factors contribute to accuracy. Crimping the best way is one of those factors. Look at your group sizes to assess accuracy. Good luck-

Old Corp · Mar 15, 2023

Not much to add to the above good advice....
I would just add to do your bullet seating and crimping as TWO separate steps.
Years ago, working at a LGS that was also 'all things reloading' we found there was often confusion over this. Believe that even some of the small pamphlets that came with some manufacturers dies were advising on setting the dies to seat and crimp together. Not a good idea, IMHO.

Good luck.

stansdds · Mar 15, 2023

For revolver ammo, as long as the bullet has a shoulder or groove, I prefer a roll crimp.

Roofuss · Mar 15, 2023

I always roll crimp my loads for my .41 mag.

WR Moore · Mar 15, 2023

Bullet seating and taper crimping in one step does have a slight advantage if you're loading for semi-autos. Since the crimp is being applied in the very last movement of the bullet into the case, you're getting a good bite into the jacket to improve the ability to prevent bullet set back during the feed cycle. Of course this works best if you don't skive the case mouth. And, bullet setback isn't an issue with revolvers.

The bench rest rifle crowd discovered that a very slight taper crimp (even on match bullets with no cannelure) improved uniformity of bullet pull and accuracy. That said, you provide much more dispersion holding your handgun in your paws than the bench rest crowd gets with sand bags/rests front & rear on the stock and 2 oz triggers.

ReloadforFun · Mar 15, 2023

Revolvers act as inertial bullet pullers for thise rounds in adjacent cylinder chambers when fired, trying to pull the bullet out of the case.

Autoloaders try to push the bullet deeper into the case by ramming the cartridges in the magazine into the front of the magazine under recoil.

The roll crimp is intened to retain the bullet from walking forward. The taper crimp is intended to remove the case mouth flare. Bullet retention for autoloaders is more a function of the expnander ball than the crimp.

rockquarry · Mar 15, 2023

As for always using a roll crimp on revolver cartridges, this will work, but if you haven't also tried taper crimping, you'll never know which method will provide the best accuracy.

As for seating and crimping in separate steps, I like to do that, too, but informal and formal testing has shown little or no difference in accuracy between the two methods, if done right. We often assume a lot without ever verifying, too often relying on conventional wisdom which may or may not be flawed.

reddog81 · Mar 15, 2023

I wouldn't worry about it too much. If you can tell the accuracy difference between a light roll crimp versus a light taper crimp on a target handgun load at 25 yards you're a better shot than 99.999% of shooters out there and should be out teaching others how to shoot.

What bullets are you using? For me - lead bullets with a crimp groove get a roll crimp. Plated bullets get a light roll crimp or a taper crimp will work. Jacketed bullets with a cannelure should work what ever is easiest for you.

Nevada Ed · Mar 15, 2023

The only time I use a heavy crimp on a lead bullet is when I load a 158 "FBI"
for my M49 snub nose with Blue Dot powder to get enough fps to give the bullet a chance to expand
or when I load a heavy lead bullet for hunting purposes.

The rest of my crimps on lead/copper bullets, is just enough to prevent, "Setback"
as well as the taper on my pistol loads, with bullets seated, deep enough.

A light taper is ok with light target loads but I will never use a light taper on a full or +P load
to make sure the bullets stays put in the case, where I seat them.

A little knowledge on crimping, is not a good thing.
Lots, is needed.

rockquarry · Mar 15, 2023

reddog81 said:
I wouldn't worry about it too much. If you can tell the accuracy difference between a light roll crimp versus a light taper crimp on a target handgun load at 25 yards you're a better shot than 99.999% of shooters out there and should be out teaching others how to shoot.

What bullets are you using? For me - lead bullets with a crimp groove get a roll crimp. Plated bullets get a light roll crimp or a taper crimp will work. Jacketed bullets with a cannelure should work what ever is easiest for you.

A blanket statement not necesssarily true. Differences can be significant enough to change procedures, but maybe not. You can't know without testing.

reddog81 · Mar 15, 2023

rockquarry said:
A blanket statement not necesssarily true. Differences can be significant enough to change procedures, but maybe not. You can't know without testing.

If true, surely someone would have done the testing and can provide a conclusive answer.

jcelect · Mar 15, 2023

Rule of thumb; revolver=roll crimp autojammer=taper crimp! Now let us look at autojammer calibers in a revolver! Case in point: 10mm auto in a 610 revolver. I shoot the 10mm in bowling pin matches and finding bullets with a crimping groove is very hard. I then crimp on the ogive of the bullet! If you ever have experienced a bullet pull in a large cal revolver, you have missed the fight of a life time, with a loaded revolver!
jcelect

RGPM1A · Mar 15, 2023

If you are going to use a speed loader or moon clips a roll crimp is much better because the rounds will fall into the cylinder a lot easier and not get snagged on the case mouth.

rockquarry · Mar 15, 2023

reddog81 said:
If true, surely someone would have done the testing and can provide a conclusive answer.

That's up to the handloader. It's like changing primers: usually it doesn't matter, but sometimes you can measure the difference in group size. If best accuracy isn't of primary importance, any method will work fine. No argument from me.

TheTinMan · Mar 15, 2023

Old Corp said:
Not much to add to the above good advice....
I would just add to do your bullet seating and crimping as TWO separate steps.
Years ago, working at a LGS that was also 'all things reloading' we found there was often confusion over this. Believe that even some of the small pamphlets that came with some manufacturers dies were advising on setting the dies to seat and crimp together. Not a good idea, IMHO.

Good luck.

Most seating dies for semiauto cartridges are designed to apply a taper crimp at the very end of the stroke. Most seating dies for revolver cartridges are designed to apply a roll crimp. Many hand loaders use this feature of their seating dies.

I always select a bullet with a cannelure or crimp groove for revolvers. However, I would not apply a roll crimp to a bullet without a cannelure or crimp groove.

Personally, I prefer to crimp in a separate step so that the bullet is not moving while the crimp is being applied to the case mouth. It also makes die setup easier for me in that I might have to tweak the crimp die for a particular batch of cases, but I can leave the seating die alone. Whether or not this maximizes accuracy isn’t something that I’ve tested.

For revolver cartridges I prefer Redding’s Profile Crimp dies to get a roll crimp. That seems to do a better job regardless of inconsistencies in case lengths but YMMV. Many hand loaders swear by Lee’s Factory Crimp Die.

Pisgah · Mar 15, 2023

Try the taper crimp. Then, write us a post about how you got the gun operable again after it was tied up by a bullet jumping forward under recoil...

No, it won't happen every time, just often enough to make a point.

richrd · Mar 15, 2023

Thanks for confirming my thoughts. I taper crimp my 45acp because that's what the gun wants and put a moderate roll crimp on one .38 revolver because it makes a noticeable difference in accuracy.

For the .41 I'll start with the slight roll crimp to find a load then experiment with the taper die.

Thanks

rockquarry · Mar 15, 2023

Pisgah said:
Try the taper crimp. Then, write us a post about how you got the gun operable again after it was tied up by a bullet jumping forward under recoil...

No, it won't happen every time, just often enough to make a point.

This is something to be tested. If you do all this haphazardly, YouTube video style for example, what you say will likely happen. I've been taper crimping .357 Magnum for a good while and it works fine. I only shoot cast bullets in handgun cartridges.

The reverse is also true, another reason to try different ways of doing things. There are few ironclad rules on any of this and it seems many expound on things they've never really worked with. An example is roll crimping .45 ACP ammo for use in a 1911 or other semi-auto pistol. This was widely practiced until recent times.

I've tried it both ways, taper crimping and roll crimping. I got ever so slightly better accuracy with taper crimping, so that's what I use. Roll crimped cartridges, however, worked fine and fed and chambered as reliably as taper crimped rounds. The Star Universal machine I used to have in .45 ACP came with only a roll crimp seating die.

Well known 1911 gunsmith and competitor Alton Dinan wrote a comprehensive AMERICAN RIFLEMAN piece in the '60s (I think) where he compared the accuracy of a variety of taper crimped .45 ACP loads to roll crimped loads by firing thirty-shot groups at fifty yards (probably from a machine rest - but I haven't read the article in a while). The roll crimped loads were at least slightly more accurate in his testing.

roll crimp vs. taper crimp

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