Factory crimp

[DesertRatR]

I thought there were two kinds of crimps: taper and roll. Then I discovered a factory crimp die. What is a factory crimp, versus a taper crimp?

[THEWELSHM]

Some would say a BS crimp for not doing it correctly? Rumor is it stresses brass? I don't know, like I said that's the rumor? Let me get my popcorn...

Thewelshm

[Pathfinder45]

Here it is: http://leeprecision.com/reloading-di...tory-crimp-die

I use one on all my 30-30 reloads. For 45 Colt I have two different ones: One that I use on all jacketed bullets and, another that I use on all short-case Hornady brass. I never crimp for bolt-action rifle cartridges like 270 Winchester.

[Nick_C_S]

Lee makes the "Factory Crimp Die." I don't know if the term is trademarked or not.

They work a little differently in rifle vs. pistol cartridges. In pistol, they perform a roll crimp with revolver cartridges (38/357; 44; etc.). With semi-auto cartridges, they perform a taper crimp.

With pistol, the only thing that makes them different than a garden variety crimp (or seat/crimp die) is that they have a "collar" at their base that'll "iron out" any bulges or other anomalies that may occur to the case during seating, that may cause feeding problems (be it into a semi-auto breech, or a revolver's charge holes). A Lee FCD only crimps and has no seating function (pistol or rifle).

With rifle, it crimps by squeezing the neck from four directions at the same time, and over most of the neck area. By design, it is virtually impossible to over-crimp and distort the shoulder. (Note: "virtually" impossible; as the lack of common sense humanity has to offer is seemingly boundless at times.)

Whether or not FCD's are beneficial or even counter-productive is a point of contention and sometimes spirited debate.

Personally, I like them. I use them for every pistol caliber I load*. Others will have a different opinion; and that's okay.

(*I often taper crimp my 38 and 44 Spl ammo. In which case, I disengage the crimp part of the FCD, but still run the cartridge through the "collar" part.)

[JeepHammer]

Roll & Taper are both functions of the seating die,
Both push the bullet straight down while crimping is happening, damaging load bearing surface on the side of the bullet more than needed.

Crimping with a seating die also tries, and often succeeds in pushing down on the case mouth hard enough to change your shoulder sizing,
In some cases actually pushing down hard enough to buckle the shoulder.

Taper/Roll crimp dies REQUIRE PRECISELY TRIMMED BRASS to be anywhere near consistent.
Since crimp is determined from the shell plate to where the crimping lip stops in relationship to the brass in the die,
Longer cases get crimped WAY harder, more brass being forced into the crimp ring,
While shorter cases get little or no crimp since not nearly as much brass is being forced into the crimp lip ring.

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The 'Factory Crimp' type dies are 'Collet' dies,
Crimping in a separate process from bullet seating, so your bullet isn't being pushed past the Crimp',
And the die 'Indexes' (is 'powered' by) the shoulder of the case instead of the neck.

This somewhat supports the neck and spreads the crimping force out over a much larger surface area.

'Factory Crimp' dies use small fingers to crimp by pushing IN FROM THE SIDE instead from down from the top, not nearly as much force needed for a solid crimp.

Since these dies apply the crimp from the side, brass length isn't nearly as important, slight variation in length won't matter too much.
This is why guys that volume reload rifle ammo like them so much, absolutely precise trimming isn't required.

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As for 'Over Working' the brass...
That depends on the amount of crimp you use, the harder you crimp, the more you work hardens the mouth of the brass, and the sooner it's going to crack.

Annealing helps, but not crimping the living daylights out of the brass in the first place is usually the best, and easiest answer.

Taper/Ring crimp is continuous pressure/Hardening all the way around the case mouth,
While there are gaps between fingers of a collet crimp allowing some relief/deflection area for the brass.
Some argue for or against either one, I personally don't see a ton of difference between either method.
I don't see any more cracks or any less cracks with either method...
OVER CRIMPING will crack a mouth faster than anything!

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AS WITH ANY CRIMP, measure the mouth outside diameter, SNEAK UP on the Crimp you need!
A little crimp goes a LONG way, most people WAY over crimp before they break out the calipers/micrometer or do any testing trying to dislodge the bullet from the case.

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Not often discussed in a crimping thread,

NECK SIZER!
A good 85% of crimping can be bypassed by simply HONING the case neck sizer a little.
This produces a SLIGHTLY smaller neck diameter, and more neck tension/bullet hold.
I've only seen a few firearms that absolutely required a hard crimp to keep the bullet from moving during loading or recoil forces.

Tightening up the neck a little WILL NOT hurt your loading process,
And if it doesn't work, you can still crimp with zero issues.
Just something to try if you are trying to reduce crimp stresses on your cases.

[Hammerhead]

Don't forget profile crimps and collet crimps.

Back in the day there were even stab crimps.

in 9mm I started with the Lee deluxe FCD die set. If you seat the bullets crooked with the poor quality Lee seating die and bulge your case, the FCD die will CRUSH them back into an acceptable round that should function.

That's one way to do it.

Another is to use better techniques/equipment to seat the bullets straight and use a normal crimp die, taper for autos, roll or profile for revolvers.

[std7mag]

I like to use a separate crimp die, as mentioned it only crimps.

I only use it for pistol cartridges, and 243, 30-06 rifle. As both of those i load for a lever and a pump action.
For my bolt guns i don't crimp.

[skinnedknuckles]

Originally Posted by JeepHammer

The 'Factory Crimp' type dies are 'Collet' dies,
And the die 'Indexes' (is 'powered' by) the shoulder of the case instead of the neck.

This somewhat supports the neck and spreads the crimping force out over a much larger surface area.

'Factory Crimp' dies use small fingers to crimp by pushing IN FROM THE SIDE instead from down from the top, not nearly as much force needed for a solid crimp.

Actually, the collet is actuated by contact between the shell holder and the die. There is no force put on the shell (neck, shoulder, or body) except the squeeze on the neck by the collet fingers. The is no longitudinal force that could cause buckling or other damage to the shell.

There are at least three different types of Lee Factory Crimp Dies. Lee Factory Crimp Pistol Dies for straight wall cases use either a roll or a taper crimp, depending on the use, and they have a carbide sizing ring set to SAAMI minimum chamber dimensions to ensure all cartridges will fit a SAAMI chamber. Lee Factory Crimp Rifle Dies for bottle neck cases are collet type and do not have the sizing ring. They also make a Short Bottle Neck FCD which is also a collet type for cartridges such as .357 Sig, but the collet actuation method is different.

[Stats Shooter]

I won't comment on the "to crimp or not to crimp" question...That is a deep rabbit hole.

But I will say that taper and roll crimping is very difficult to get right. I have tried to do it for my AK and AR's. As others have said, taper and roll crimping requires precise trimming, otherwise you WILL push the shoulder out on bottle neck cases that are longer, and won't put much of a crimp on shorter cases... If they do chamber, there is no way you can get a consistent bullet hold.

I personally do not crimp anything except my 45-70 lever action rifle, but I use a factory crimp die and cannalure bullets when I do crimp because even when I have trimmed, and setup a roll/taper crimp die properly, I still got erratic velocities and reduced accuracy.

[mikld]

This always brings up many comments. First, Lee makes a "Factory Crimp Die" for handgun cartridges. It is a "post seating/crimping sizing die" that hides mistakes. The second FCD Lee makes is for rifle cartridges. This is a collet crimp die (an internal collet squeezes the case mouth around the bullet). Big difference between between the two. The confusion comes when a poster just says "Lee FCD" and doesn't specify which. There are some collet FCDs for handgun ammo, but that's the exception (I use on for my .44 Magnum).

Crimping 101; roll crimps are most often used on bullets that have a cannalure or crimp groove and used in revolvers and tube magazine fed rifles. A taper crimp is a slight taper applied to cases with smooth sided bullets to squeeze the case mouth down to the bullet, most used in semi-auto handguns. A collet crimp is a die with an internal collet that puts a straight squeeze on the case mouth used most often on rifle cartridges, and limited availability for some handgun cartridges. Of course there are variations and exceptions, but this is the basic "rule of thumb"...

[T. O'Heir]

"Factory Crimp" is marketing by Lee. Nobody else has bothered to come up with their own version.
"...trademarked or not..." No mention of it on Lee's site. No 'circled TM' next to the phrase either.

[DaleA]

Thank you Mikld for the information.