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Discussion Starter · #1 ·
Could somebody please edumucate me on crimps? I'm getting into reloading and don't quite understand the difference between the crimp you get from the seating die in the set and the factory crimp dies you can buy?
I'm gonna be reloading 45-70 to shoot from a 1895 sbl and a ruger number 3. And 357 from revolvers. The guy at the reloading shop either didn't have the time or he couldn't think of a way to explain why we needed the factory crimp die for the 357 even though he said its a better crimp than in the seating die.
 

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Some seating Dies have a Tapered Crimp. Not all. It can be slightly adjusted but it is near impossible to even see. A Factory Crimp Die does a much better job and can be adjusted to give more or less crimp much more easily. And you can see the crimp.

For ammo that needs to be crimped go with a Factory Crimp Die. They are cheap and the one more step doesn't take long at all. I do all my .35 rem, and AR ammo.
 

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The crimp supplied in most seating dies is a roll crimp... this is, it 'rolls' the top of the case into the bullet. The upside is it provides a very secure crimp for big Magnum loads or for cartridges going into tube or box magazines. The downside to roll crimping is too much roll crimp you can buckle the case, too little and the crimp won't be effective (or even crimped at all; ) the case overall length is the determining factor.

Other crimp dies like the taper crimp (what I use generally) and the 'Factory Crimp Die' (or FCD) are less severe and less sensitive to case overall length. The taper crimp 'deflects' the case mouth into the bullet much like a roll crimp, but at a much less acute angle. It is easier on the brass and provides enough crimping force for all but the heaviest loads, even for tubular magazines.

The FCD uses a collet that 'squeezes' a ring crimp into the case, it is the least sensitive to case overall length.

Most rounds don't require super heavy crimp to be effective. There is some debate about bullet deformation and accuracy because of too heavy a crimp (any crimp.) I used to be a heavy crimper but anymore I've gotten away from it, using light taper crimps in most cases and only resorting to the roll crimp for my Magnum handgun loads using W296. The idea is to knock the flared case mouth back in juuuuuust enough to grip the bullet... without deforming it. In many cases (rifle rounds) I don't crimp at all, relying on proper case neck tension to grip the bullet... this is in rifles like my AR and M1a.

In your case, for the .45-70, I would use a very light roll crimp, or if you wanted to spring for another die, a very light taper crimp. If you have good case neck tension in your cases, you wouldn't even need a crimp for the Ruger #3.

In the case of the .357, I would go taper crimp all the way, unless you were loading heavy Magnum loads.

I only have 1 FCD, I use it when I'm loading the big .348WCF rounds for my lever gun. I have issues with case length and the FCD works pretty well in this instance.
 

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Discussion Starter · #4 ·
That sheds some light on the difference. Thanks
 

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I have for many years, simply used the standard 3 die set for straight wall cases such as used in most handguns and in the 45/70, and properly adjusted there is never a need for a 4th die.

It may not take much longer to add a "FCD", but the properly adjusted three die set takes less.

Crusty Deary Ol'Coot
 

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Well, SIRJ, how do you like your edumucation so far? I use bullets that have a cannelure, except for my .45AUTO loading, that circumferential depression that the case mouth is "rolled" into to secure the bullet, and a tapir crimp die for the .45s. I use the LEE FCD to crimp my .35 Remington stuff because the carts feed from a tube mag. The thing that's equally important, no, more so, is the security from movement that case neck tension, as charlie98 mentioned, provides. jd45
 

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An aspect to watch is overall case length. Best accuracy, depends on among other things, consistent neck tension/consistent crimp. The way to get a consistent crimp, is to insure all the cases in a batch of reloads have the same case overall length. If some cases are trimmed to minimum COL, and they are mixed with cases that have been fired a time or two and are longer, then the crimp comes up inconsistent. Worse case scenario: some could be over crimped, and some not at all.
 

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The taper crimp die was designed to be used on pistol cartridges that headspace on the case mouth such as the .45 ACP and 9mm Parbellum. The idea is a roll crimp changes the case length however so slight which also effects the headspace. If the headspace is shortened too much you may have a failure to fire. The taper crimp die squeezes the case body down so that it puts more tention on the bullet.

Hip
 

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The taper crimp die was designed to be used on pistol cartridges that headspace on the case mouth such as the .45 ACP and 9mm Parbellum. The idea is a roll crimp changes the case length however so slight which also effects the headspace. If the headspace is shortened too much you may have a failure to fire. The taper crimp die squeezes the case body down so that it puts more tention on the bullet.

Hip
Thanks, Hipshot... I forgot to mention autoloader headspacing. The OP was talking about (I was assuming...) revolver loads for the .357, but it's a good point. My first taper crimp dies were for the .45ACP, but I found they didn't tear the brass up as much (from my old heavy-handed crimp days...) and I wound up buying them for pretty much every cartridge I load for... pistol, autoloader, and rifle.

I have for many years, simply used the standard 3 die set for straight wall cases such as used in most handguns and in the 45/70, and properly adjusted there is never a need for a 4th die.

It may not take much longer to add a "FCD", but the properly adjusted three die set takes less.
One of the reasons I bought the Hornady Pro-Jector was FOR the 5th station... so I could run a separate crimp die without any extra effort. But to each his own... :)
 

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... The downside to roll crimping is too much roll crimp you can buckle the case, too little and the crimp won't be effective (or even crimped at all; ) the case overall length is the determining factor....
and any variance in case length will cause differing levels of crimp. if case lengths are identical, roll crimps are awesome. if not, the FCD is unbeatable. it's called the "factory crimp" die because that's how the factories do it.
 

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In a nutshell, a roll crimp is for revolver/rifle rounds (with a rim) and bullets with a crimp groove, better known as a cannelure. Taper crimp dies are for auto cartridges that are supposed to headspace on the case mouth, since they don't have a rim, and many bullets used in those guns don't have a cannelure. The roll crimp folds the mouth into the crimp groove and holds it against the forces of recoil, so your bullets don't pull loose and move forward, which can tie up the gun if they extend past the front of the cylinder.

In autopistols, the taper crimp forces the case mouth against the bullet, holding it tighter than neck tension alone generally does. In theory, the case mouth sets the headspace, but in most autopistols the extractor is what actually holds the round in place, and the case mouth is many thousandths from actually coming in contact with the end of the chamber. As an example, the 45ACP's case length is listed as .895", but I have been measuring them for 25 years, and have never seen one that long.......new or used. Add to that the fact that most 45ACP brass tends to shorten on firing, and you see why the crimp is less relevant. Necessary, but not for headspacing.

Tubular magazines need bullets that are properly crimped so the spring pressure doesn't force bullets down into the case, raising pressures and ruining accuracy. The other reason for a good crimp, particularly with the slower powders, is that smokeless powder is "progressive burning". That means the more pressure, the more uniformly and consistently it burns. In a round with a wimpy (or no) crimp, the pressure builds less rapidly, and the bullet can begin to move forward before the pressure has built to the proper level. It's called "Shotstart Pressure," and it's important if you want consistent ballistics, which leads to better accuracy.

The only time I use a Lee FCD is when I'm using rifle bullets with no cannelure, or those I choose to seat to a non-standard length, meaning the crimp is in the wrong place for what I want. They're also a great help with lead bullets, since they "stab" a crimp into the softer bullet.

That's the quick & dirty version of how it works. When loading cannelured bullets in revolver rounds, I seat and crimp in the same step, because I think it does no harm, and it's faster. If accuracy is the primary concern, I'll crimp in a separate step, making sure all the cases are the same length, so the crimp falls into the groove the same way.

Reloading for accuracy is all about consistency, and the more variables you can take out of the equation, the better your accuracy will be.

Hope this helps.
 

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Discussion Starter · #12 ·
Wow so much info. Thanks everyone.
 

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There is no way to heavy a crimp on large diameter bullets will affect accuracy, if it does, your bullet design is totally wrong. I crimp every cartridge I Handload for with a Lee Factory Crimp Die, (LFCD) some Lee custom makes and some I custom make. If you want consistency in bullet placement you will crimp with a LFCD. This is a Beartooth 325LCMN bullet that's shots great in our 444's it's crimped right for consistent accuracy, I view this as a Medium crimp, the top line is the crimp from the LFCD.
 

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Starrbow,

Not quite sure what your showing us in your photograph.

Are you saying that the Lee collet "FCD" forced that upper groove into the bullet?

No offense intended here Starrbow!

SIRJ,

Not being one that has a love affair with the Lee Collet FCD, I will say that it is, from everything I read, much better then the FCD with the carbide ring in the mouth which can lead to undersized and deformed cast bullets. And yes, I have been there and done that.

Also, and of course this is just my Ol'Coot's opinion, but I could crimp to bullets crimp groove (shown above) with no problems and great success with the simple use of my standard three die set of .444 dies.

Give the properly adjusted three die set a try, millions of folk have successfully already done so before you, and "IF" there is a proven problem, then using your tests to establish a solid base line, possibly try the FCD. The Key is, "properly adjusted."

Crusty Deary Ol'Coot
 

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Lee makes two kinds of LFCD, pistol and rifle, pistols are a similar crimp as a roll crimp, the die and crimped are stationary and the bullet/ case moves during crimping, I never used one, I only use the LFCD that has the collet that moves with the bullet/case, until it sees the top of the stroke, at that point the crimp is done. No way, shape or form that a properly adjust Collet type die deform a bullet enough to hurt it, that would mean the driving band would be about .020 wide and your crimping absolutely on it, not likely. Yes that top line is the crimp on that bullet!
 

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Starrbow,

If you read my last post, you will see I am fully aware of the 2 types of Lee "FCD" and the fact that the type without the collets can be a problem causer.

However, being the old coot that I am, I have used the standard 3 die sets for years and always successfully so have yet to see the need for a 4th die in the form of the collet style "Factory Crimp Die".

If I did, I be jump'in on the Lee band wagon right along with you.

I did use the Lee carbide ring FCD on .45acp cast bullet loads, and it took me weeks to figure out the reason for the failure to function issues I was having. I used one of those dies successfully with a .40 S&W, but it was the total pits with the .45. So at best, that style of FCD is a sometimes thing.

Some folk say to remove the carbide ring, but then what is the point of the 4th step, when my three die set always has done the job in three steps

I understand that the collet type works well for many folk, but as said, my use of the standard 3 die sets has always been successful so I see no point in again adding a 4th step to the process.

I have never owned or used a centerfire pump or semi auto rifle, so simply never have seen a need to crimp any rifle ammunition other then that used in a .44 Marlin lever action which used the same ammo as loaded for my RUGER RedHawk .44 and the 45/70 ammo loaded for my RUGER #1 where I give a bit of a crimp in the standard 3rd die the interest of a more complete powder burn.

In both cases, the crimp is simply applied with the bullet seater/crimp die in the three die set.

Please know that I'm in no way trying to ruffle anyone's feathers here, least of all yours. But sometimes newer handloaders feel almost forced into buying tools that may or may not be needed. When in fact they should have waited until use of and learning the basics might have been all that was needed.

If there is a proven need for an additional die, by all means buy it, but in almost all cases, simply properly adjusting the 3 die set will be all that is needed.

Crusty Deary Ol'Coot
 

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I hear and understand you, Factory rifle ammo is not roll crimped, it looks real close to a LFCD type crimp, wonder why?
 

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Starrbow,

Will need to take your word for the factory ammo resembling handloads crimped with the Collet type FCD.

Reason is, I likely haven't fired 10 rounds of factory centerfire rifle ammo in the last 30 years and not much during even the previous 10 years.

A little bit in handguns verifying functionality in carry guns, but for everything else it has been almost totally handloads for may years.

When I began handloading, the comparison with factory ammo was simply something that I could easily out do with my hand loads.

Now days, maybe not so easy due to the increased quality of at least some factory fodder, but I have been at the game for so long now I'm not likely to stop while I'm still able to move and shoot. Handloading is what I do.

Have a great day!

Crusty Deary Ol'Coot
 
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