When to taper crimp ?

[Lefty Red]

This question is for jacketed bullets. Sorry, didn't see another forum for them.

I traded for several jacketed 44 bullets and was going to load up some. In the past, I always used a roll crimp with the jacketed canalure (sp?) (its French for indented band another bullet to grip case) . But I was wondering, after really looking at them, that they are not that deep and maybe I will damage them if I use a roll crimp on them. I have extra taper crimp dies, but was wondering if the taper crimp would be too light?

BTW, I have a LEE collet type crimp die on the way! So this question might be obsolete come next week. But was just wondering. Because as of now, I only taper crimped smooth sided casted and jacketed and roll crimped everything else.


Jerry

[NC_JEFF]

I don't taper crimp any of my straight wall brass, 38, 45Colt, 44 etc...and the roll crimp should be just enough to prevent the bullet from moving under recoil. (which is a fairly heavy crimp for 44 magnum).

[Tatume]

Taper crimp rimless cartridges that headspace on the case mouth. A roll crimp would not leave a surface to headspace the cartridge.

[leftiye]

Never. I don't have a single taper crimp die. Auto pistol ctgs. maybe, but a slight roll crimp behind the front edge of a lube groove does it every time. Sizing down the boolit ain't a mucho smart thing to do anyway. I would vote for the FCD for the cast without crimp groove.

[Blackwater]

Your standard seater/crimp die is ADJUSTABLE, and you have to adjust it to get it the crimps just right. That's why they make them like they do. Many cast bullets have deep crimping grooves cast into them, but jacketed are usually shallower, so you just have to adjust your die accordingly. It's really no big deal, and once you've got your die set up just like you want it, make up a dummy round with the bullet you're using, and use that to set your crimp and OAL. Takes a lot of diddling out of the equation. Most die boxes have room for several of these dummy rounds in them for organization and safe keeping purposes.

[mdi]

Rule of thumb; when a bullet has a cannalure or crimp groove, roll crimp. If a bullet is smooth sided, use a taper crimp. But someone will tell us of exceptions, but this is just a "rule of thumb". You can roll crimp into a cannalure but it will be much less than rolling a crimp into a crimp groove on a cast bullet. Trying to put a heavy crimp in a jacketed bullet with cannalure can result in buckled cases, so go easy. BTW; a medium roll crimp should hold bullets from creeping during recoil (I loaded Sierra 240 gr JSPs way up to near max. when I had Magnumitus)...

[gwpercle]

Roll crimp into the cannelure just enough to dig into the ridges, I would call it a light crimp. If the crimp is too deep you will get a buldged neck. Crimping is one of those things you have to play with, start with light crimp, shoot a few and see if the J-words stay put, If not, apply a little more and try again.
Gary

[DougGuy]

Generally, taper crimp is only needed with auto pistol ammo.

Not to hijack the thread Lefty Red, but your Lee collet crimp die might need some adjustification when you get it. the crimp band is real wide on those, and they will crimp not only the case mouth, but the boolit just in front of the case mouth as well, which is not a good thing. I love the collet crimps for heavy boolits, they are a foolproof crimp well suited for dangerous game where your life may depend on your pistol as a last defense, and you cannot under ANY circumstances abide with ANY amount of boolit pull.

Here is how I configure mine and they work very well afterwards:

http://castboolits.gunloads.com/show...=1#post2239315

.45 Colt 300gr RF boolits crimped with the modified collet crimp die:

[Lefty Red]

No worries! I was going to get ahold of you when I got anyways. Your thread on it is what got me thinking of it.

I am only going to be using the collet die on jsp/jhp's so I hope it doesn't need modifying, but I will get ahold of you about the technique.

Jerry

[Lefty Red]

So, does the jacketed bullets that have the light cannelure need a taper crimp or will the roll crimp tear the jacket?

[DougGuy]

Well if they are light, that means they won't be pulling at the crimp really hard so a roll crimp outta do it. If you force a roll crimp hard enough, it will swage the case mouth into the side of the boolit and so a cannelure that isn't real deep it will just push it deeper. Plated boolits might tear the plating if you crank a roll crimp into them that hard but a jacketed boolit should be perfectly able to take a firm crimp.

[TXGunNut]

If there was any doubt DougGuy nailed it. Rule of thumb; fast powders need little crimp. Slow powders need a bit of crimp to get the party started.

[Motor]

Jerry. Did you ever specify what type of firearm you were loading them for?

If so I must have missed it.

The reason I ask is a taper crimp could never hold a bullet from moving forward like they attempt to do in a revolver unless perhaps the loads were very light.

If your jacketed bullets have a canalure then roll crimp them. If you do it correctly you will not damage the bullets.

A taper crimp on a hard jacketed bullet is practically useless anyway. The object you are trying to crimp is stronger than what you are crimping it with. Plus the brass will spring back ever so slightly while the bullets won't so if you squeeze it too hard you defeat the purpose of crimping in the first place.

Motor

[mdi]

So, does the jacketed bullets that have the light cannelure need a taper crimp or will the roll crimp tear the jacket?

Roll crimp into cannalure, crimp grooves. Taper crimp on smooth sided bullets. No more than that. Don't overthink the process. Once you get the hang of it, you can tweek more or less crimp as you please...

[Bigslug]

A roll crimp would be to keep bullets from pulling out under recoil in a hard-kicking revolver or dangerous game rifle, or to keep them in place under recoil in a tubular-feed lever action. It typically doesn't take much (remember, there's natural neck tension too), and if you overdo it, you can deform the bullet or get an outward bulge that may prevent seating in a tight chamber.

A taper crimp will typically be for the mouth-headspacing used on most auto pistol rounds, single shot rifles where recoil-pulling is a non-issue, and slick-sided slugs. You have enough when it takes the bell out of the case mouth that was placed there to get the bullet started into the case - one of the common causes of autos not feeding is insufficient taper crimp.

Reliable ammo is goal #1, but amount of crimp/neck tension can be a player in achieving target-grade accuracy as well.

[Blackwater]

Big Slug has it nailed. Only thing I can add is that within each crimp type, you can (and probably should) vary the degree of crimp according to the powder type you're using. Fast powders often like a lighter crimp, while slower ones usually like a heavier one. This can vary too, according to how large and deep the crimp groove is, and how much recoil the load has. It just takes a little thought to work it all out so that the load works. I know most of us are in a perpetual hurry, but loading good ammo, that you might have to use to defend your life with, kind'a indicates that a few seconds adjusting a seater/crimper die just might be a good idea, and worth all the "trouble" it takes. Learn to do it right, and it's really quick and easy, and not much real trouble at all. FWIW?

[Walkingwolf]

Barrel rifling does not tear the jacket, why would a crimp. I use a stiff crimp on all rimmed cartridges, even with plated bullets. I have recovered plated bullets and there never has been any plating separation. I did have problems with I first started using plated bullets with inconsistent accuracies using a light crimp. And after the first squib on a target load I learned my lesson. My readings are usually no more than 50fps separation, and the normal is around 20fps. I also use a good stiff taper crimp on semi auto rounds, and get the same consistency, and accuracy as with rimmed cartridges.

Actually I have found that jackets and plating is very tough when smelting down fired bullets. The jacket are not a problem because the are either open on the top, or bottom. The plated bullets need to be cut with dykes to keep them from popping in the pot, possibly causing injuries. The plating is darn tough, and jackets are a hell of a lot tougher.

[mongoose33]

Roll crimp into cannalure, crimp grooves. Taper crimp on smooth sided bullets. No more than that. Don't overthink the process. Once you get the hang of it, you can tweek more or less crimp as you please...

In my opinion, this^.

Also IMO, taper crimp is an unfortunate term. For straight-walled cartridges (9mm, .40 SW, .45 ACP e.g.), the purpose of "taper crimp" is to straighten out any casemouth expansion. It should, in those situations, be called "casemouth expansion straightening" or some such.

Some "straightwalled" cartridges--like .38 spl or .357 mag--need the roll crimp to keep the bullet from pullout out and jamming the cylinder.

[Lefty Red]

Motor,
Sorry, its for both a single shot and revolver.
Thanks for the guidelines!

Jerry

[Motor]

Ok Jerry then I'd suggest the roll crimp.

mongoose33 gets it. I've been preaching this every chance I get. There are some terms with multiple meaning in reloading. Crimp is one of them. You can crimp a bullet by displacing some part of the brass case into an area on the bullet provided for this purpose. You can also roll the case mouth directly into a cast bullet and achieve a functional crimp.
Taper crimp on the other hand is tool related. The tool is a crimp tool but considering it's true purpose it should, as mongoose33 stated, be named a mouth flair removal tool. Yes I know that's not a direct quote but you get the idea.

I think to even muddy the waters more they make taper crimp dies for rifle calibers like .223 but again there is a purpose and the purpose is the same, remove mouth flair. Now some may be asking why does a .223 need a mouth flair and the answer is it's for loading flat base bullets like the Hornady 55gr SP on a progressive press. The mouth flair allows almost guaranteed easy automatic bullet feed.

Have you ever wondered why almost all factory rifle ammo is crimped? It's because all the case mouths are flared so there are no bullet seating issues on the automated machines.

Motor