bullet seat and crimp verses factory crimp die

[georgiacatweazle]

I know this has probably been around the forum allot.

I was about to invest in 9mm and 38 special factory crimp dies for my lee breech lock single stage.

i hear some people say it's a must have and others not so.

i personally haven't had too much trouble adjusting the combo bullet seat die, but wondering if overall my ammo will be of a better quality, more uniform and run better ?

i may end up getting a turret press this year so not too worried about adding an extra step.

thanks.

[Bart B.]

I and others don't use FCD's on those cartridges and have no problems. Therefore, they're not mandatory. Factory commercial ammo is made without them, too.

[steve4102]

I use the Lee Factory Crimp die for all my handgun ammo. When set up properly and used correctly it is no better or no worse than any other stand alone crimp die. Unlike other stand alone crimp dies it has a carbide sizing ring at the base. This ring will ensure that all your handloads will fit-n-feed.

Great tool and an excellent addition to any reloading bench.

As this thread grows you will find that the LFCD is either loved or hated. You will also find that most of those that "hate" this wonderful tool have never tried it. Go figure.

[georgiacatweazle]

after thinking about how the combination bullet seat die works, if you have anything other than a very light crimp, i would imagine the crimp stage to possibly dig in to the bullet as it's being seated as the two events are happing simultaniously. could cause minor deformation of the bullet ?

[Bart B.]

You're right.

The accuracy of handgun ammo isn't precise enough to reveal the crimp's effect of unbalancing the bullets. Sometimes a heavy crimp produces more uniform pressure curves with real slow handgun powders. As crimp's add another variable to ammo performance, the least amount to meet your objectives is best.

Some 38 Spcl +P jacketed ammo has heavy crimps on heavy bullets. Wadcutter, mild match ammo has minimal crimp.

[mikld]

after thinking about how the combination bullet seat die works, if you have anything other than a very light crimp, i would imagine the crimp stage to possibly dig in to the bullet as it's being seated as the two events are happing simultaniously. could cause minor deformation of the bullet ?

Yep also crushing the case happens often. FWIW; I would suggest, even though you have a single stage, to seat the bullets then readjust the die and crimp, no big deal I did 50 at a time (seat 50 then crimp 50). Not as slow as some would have you believe. You can control both operations more if done individually. After you get a few rounds under your belt you can try seating/crimping at the same time, but for now, I'd suggest separating them (I started reloading pre-web and I separated seating/crimping for a few years before I read that some combined the process. I also read on many forums about bulged brass, shaved and distorted bullets by new reloaders having trouble figuring out the balance of bullet movement and crimp application).

Now this is my experience with Lee FCD; If your dies are properly adjusted, then there is no need for a post seating/crimping sizing of the cartridge. I have never had a cartridge that would not chamber that re-sizing would fix, cover up mebbe, but not fix. My whole problem is new reloaders are told to use an FCD, rather than told how to properly adjust their dies. Case bulge? Just re-size it, iron out the problem rather than solve and fix...

[Jim243]

For handgun ammo a separate crimp die is not necessary, even revolver ammo can be crimped with the seating die for a roll crimp.

HOWEVER, (there is always a however), I always use the FCD not so much for a crimp, but to insure the mouth flare from the powder through die has been remove so all cases will feed without hanging up on the chamber of the handgun and avoid ANY feed issues from the magazine.

For me that is the "Priceless" part of using the extra die.

Stay safe and shoot straight.
Jim

[Lost Sheep]

Wealth of information in the four threads at the bottom of this post.

Lee's FCD (Factory Crimp Die) performs two functions. Crimping and post-sizing. The two operations are independent of one another and cometimes work at cross-purposes. With lead bullets, sometimes the post-sizing reduces the grip the case has on the bullet. The grip the case has on the bullet is important for three reasons.

1) It keeps the bullet from being knocked deeper into the case during handling and very important, during feeding. This is most significant in autoloaders

2) It keeps the bullet from being pulled out of the case during handling, and very important, during recoil of its brother rounds. This is most significant in revolvers.

3) It keeps the bullet from moving out of the case until a threshold of pressure has been reached. This is most significant with slow powders, but important with all powders.

In taper-crimped cartridges as well as roll-crimped cartridges, the bullet tension (the grip the case has on the bullet) is provided by friction more than by (roll) crimp. If you post-size a case onto a lead bullet, the case springs back more than the lead does, reducing bullet tension. This is less problematic with jacketed bullets than with lead, but can occur with either.

If your dies are adjusted correctly, the Lee FCD will NOT post-size your loaded cartridges. You will be able to tell if it is by carefully feeling the resistance as you run the cartridge into and out of the die.

The main reason for the existence of a crimp die that operates separate from the (usual) seat/crimp combination die is to simplify installing and adjusting those dies and to prevent the case mouth from digging into the sides of bullet as it is being seated. (This can happen with a strong crimp - mainly roll crimp - on a bullet while it is still being pushed deeper into the case by the seating plug. This is virtually unavoidable with the combo die, but if it is moderate presents no problem.)



Not necessary 99% of the time, but convenient.

Lee Precision's thoughts on the matter can be found in these threads:

One thread contains a lively discussion of the FCD and the function of the post-sizing carbide ring in the FCD. The phrase "9mm" is in the thread title, but don't let that dissuade you. It contains responses direct from Lee Precision, too. Read the whole thing. It is worth it.
http://thefiringline.com/forums/showthread.php?t=465091

this thread contains a poll

http://thefiringline.com/forums/showthread.php?t=465603

Lost Sheep


The Virtue and the Vice
http://thefiringline.com/forums/showthread.php?t=509934
http://www.thehighroad.org/showthread.php?t=691050
http://www.rugerforum.com/phpBB3/vie...?f=11&t=168362
http://rugerforum.net/reloading/6586...tml#post814465

[Gravedigger56]

HOWEVER, (there is always a however), I always use the FCD not so much for a crimp, but to insure the mouth flare from the powder through die has been remove so all cases will feed without hanging up on the chamber of the handgun and avoid ANY feed issues from the magazine.

The main reason for the existence of a crimp die that operates separate from the (usual) seat/crimp combination die is to simplify installing and adjusting those dies and to prevent the case mouth from digging into the sides of bullet as it is being seated. (This can happen with a strong crimp - mainly roll crimp - on a bullet while it is still being pushed deeper into the case by the seating plug. This is virtually unavoidable with the combo die, but if it is moderate presents no problem.

So in other words, If you have one use it. If not, then save your money and spend it on another component.

[georgiacatweazle]

lost sheep, thanks for the info. so i was right about how the combo die was potentially working, as you pointed out, was a possible digging in to the bullet.

[44 AMP]

if you have anything other than a very light crimp, i would imagine the crimp stage to possibly dig in to the bullet as it's being seated as the two events are happing simultaniously. could cause minor deformation of the bullet ?

The main reason for the existence of a crimp die that operates separate from the (usual) seat/crimp combination die is to simplify installing and adjusting those dies and to prevent the case mouth from digging into the sides of bullet as it is being seated. (This can happen with a strong crimp - mainly roll crimp - on a bullet while it is still being pushed deeper into the case by the seating plug. This is virtually unavoidable with the combo die, but if it is moderate presents no problem.

If your crimp die is digging the case into the bullet, you have not adjusted it correctly. Done right, it simply does not happen.

The bullet is NOT pushed deeper into the case, cases are pushed up over the bullet. When you run the case with the bullet into the die to seat the bullet, the seating stem stops the bullet, and then the case is pushed up around it. When the bullet seating depth is correct for the crimp, the crimp groove is level with the crimping shoulder in the die body, so that when the case is bent by the die shoulder (roll crimp) it goes into the crimp groove on the bullet.

If your cases are digging into the bullet, you have the die adjusted to begin crimping "too soon".

in order for seat and crimp in one step to work properly, cases must be the same length, and the seating die must be correctly adjusted. Do that, and you are golden. Don't get it quite right, and you have a host of irritating things, like buckled shoulders, wrinkled case necks, and rounds that will not chamber.