Demystify cast bullet crimping for handguns

[ryan richards]

Dear: Cast Bullet Oracles (CBOs).

Here is an easy one for you.

Can you demystify cast bullet crimping for handguns?

Lee sells a Carbide Factory Crimp Die for $22 and says, "A firm crimp is essential for dependable and accurate ammunition. " They've got them for the 380 ACP and the 38 Special. It sounds like something I need to put on my list for handloading stuff.

Questions:

1. Do I need one of these "Carbide Factory Crimp Dies" for 380 ACP pistol and
38 Special revolver cast bullets?
2. What's the purpose of crimping?
3. What happens if I don't crimp? Will the bullet fall out?
4. Is it used with a sizing die?

Thanks for your time and interest.

Ryan

[docone31]

Most dies that I have ever used will crimp. I never got a Factory Crimp Die yet I could still crimp my ammo. Rifle, pistol, the final die will crimp unless it is a collet die.
I have never needed, nor missed a Factory Crimp Die.

[HeavyMetal]

The Lee Factory crinp die started out for rifle rounds. It worked well and people started asking for it in the pistol rounds.

The truth is most revolver dies will have a crimping function built, 38 special for sure, and most auto pistol dies are set up with some form of Taper crimp.

I'd buy a set of dies load some ammo, following the instructions, and then worry about special crimping tools if I couldn't hit the barn door!

[ANeat]

When you reload a bullet the mouth of the case gets flared out to accept the bullet. This is really inportant with a lead bullet.

When you crimp for a semiauto you basicly straighten out that flare, perhaps a few thousandths of taper cimp but not much.

On a revolver a roll crimp is used to keep the bullets fron backing out of the case while the gun is being shot.

Some of the factory crimp dies you really need to be carefull with. Especially a case without a lot of taper. Many times if using a lead bullet the FCD will actually size your bullet down a thousanth or two.
All that carefull casting and sizing withh be thrown out the window as the factory crimp die "undersizes" your bullet.
Usually resulting in leading or bullets tumbling when fired.

[Cloudpeak]

Revolver rounds really "crimp". The case mouth is "rolled" into a groove to keep the bullet from jumping ahead and tying up the cylinder.

On a semi-auto that headspaces on the case mouth, the case mouth bell that is formed to allow easy feeding of the bullet base into the case mouth (and to prevent shaving jacket material or lead), is removed. It doesn't add to bullet holding (IMO), just makes sure that the cartridge will feed properly. Even though it is called crimping on semi-autos (for simplicity's sake), it's not a genuine crimp as used on revolver rounds.

When I had any problem with case tension and the ability to keep the bullet at the set depth (aka: setback), I measured the expander plug, chucked it into a drill press and, using fine sandpaper and red and /or gray Scotchbrite, polished the plug diameter a bit smaller. I'd then load up dummy rounds and chamber several times and check for setback. Some folks just push the bullet on a solid surface and see if the bullet moves into the case. I like rechambering the same round 6-8 times to see if the COAL (cartridge overall length) gets shorter.

Anyway, I've loaded and shot thousands of rounds of semi-auto ammo and never used the Lee die. I know some, here, use them and like them. I just never saw the need.

Cloudpeak

[miestro_jerry]

I taper crimp all of my semi auto rounds, my revolver rounds are a different story, they get a roll crimp. In some cases I use the crimp in the final die of the set to crimp the bullet and the case together, while other times I may have a 4th die to do a good crimp.

I crimp 357 Mag, 357 Max and 44 Mag really tight. Then there will be no loosening of the boolits when a round is fired and the other rounds are in the cylinder.

All of my rifle rounds are crimped, some tapered like 308 Win and others are roll crimped like my 45-70s.

There is also a thought that a strong crimp will increase the case pressure and may give you a little bit bigger bang. Never really chronographed the differences.

Jerry

[DLCTEX]

I use the FCD on rounds for auto and the seating die to crimp for revolver, seems to work best for me. DALE

[Ricochet]

I think the Carbide Factory Crimp Die is a good thing especially for autoloaders. If you have a case bulged due to oversized boolits, it'll size it down to maximum overall cartridge dimensions. Won't undersize the boolit. It'll also bail you out if you've roll crimped revolver cartridges with some of the boolits not seated right to the crimping groove and bulged the case behind the crimp, preventing chambering.

Lee's current pistol dies for autoloaders can provide the same taper crimp as the Factory Crimp Dies in the standard seating die. Don't have to have the FCD unless you have case bulging issues. Their seating dies for revolver cartridges are said to initially apply a taper crimp, progressing to a "modified roll crimp" if you crimp them heavily. Not the abrupt roll crimp of the old Lyman dies, which are so critical for consistent case length to get consistent crimp.

The collet type Factory Crimp Dies for rifle cartridges are totally different devices.

[PatMarlin]

What's your favorite crimp for Keith boolits?

[Dale53]

Keith bullets are designed to accept a good roll crimp.

I use four die sets mostly. I MUCH prefer to seat the bullet and crimp in a separate die. I use the Lee FCD for the fourth die. I really wish that they had the Lee FCD when I was shooting IPSC. The effect is if each and every cartridge has been "gauged" for proper chambering.

Dale53

[prs]

One handicap we "boolit" shooters have is that most loading die sets are designed for copper condom boolits and the internal sizing of the case is often such that our lead boolits are slightly deformed when we "mash them in thar". Lead boolits are poor resizing dies! This yields a lesser retention of the boolit in the case and I do not think crimping in excess will do much to correct that - in fact, I think crimping in excess will further reduce boolit retention/pull. RCBS makes some revolver internal case sizing dies (Cowboy series or such) just for lead pills and I bet others do too. In 45 Colt they even have two in a set - one for 452 and the other for 454. I crimp very modestly and prefer the traditional roll crimp over the modified roll/taper that the factory crimp makes. I roll the lip in just to where it contacts the bottom of the crimp groove and no more, the case to boolit fit gives the most consistent "pull resistance" -- its consistency that you want mostly.

prs

[44man]

All that is needed in a revolver is just enough crimp to keep boolits from moving under recoil, no more. Case tension on the boolit is more important unless you are using soft lead that can be sized by tight brass. A tight crimp on a soft boolit can also size the boolit as it goes through the crimp portion.
The FCD can ruin brass and shorten it's life. It makes a permanent crease in the brass that is not good for lead boolits
Get away from dead soft boolits and rely on case tension for accuracy.
Use the roll crimp in the seating die, it even works with oversize boolits. Extra crimp dies like the Redding profile crimp die can size boolits if oversize.
What is a carbide FCD anyway? There is no carbide in them!

[Ricochet]

There is a carbide ring in the base of the carbide FCD that sizes the outside of the case to SAAMI maximum overall cartridge dimensions so you won't have problems chambering the round. Doesn't undersize anything. The crimp is a taper crimp in autoloaders, for revolvers it's a taper crimp transitioning to a gentle roll crimp if you tighten it way down. Not near as severe as the roll crimp on Lyman seating dies. The collet Factory Crimp Dies for rifle cartridges are different. Pistol Factory Crimp Dies don't produce creases in brass. They probably should have named them differently, since they're totally different devices.

[Dale53]

44man;
I believe that you will find a carbide ring in the base of the Lee pistol FCD. This insures that the outside case diameter of a loaded round will not exceed SAAMI" standards.

Dale53

[Sprue]

I too like to seat and crimp in two different stages. The FCD occupies the 4th hole in my Dillon and Green Machine. I have a FCD for most calibers that I load.

A light crimp is good and assures better powder burn as well. I have a friend that doesn't crimp his 38's at all. His fired cases come out looking quite blackened.

Its just a personal preference thing. What works for you may not for others. We've all been down the same path before at one time or 'nother.

[Bass Ackward]

I have run extensive tests on crimps time after time. I can see a difference in many scenarios. One is larger advantages in shorter barrels compared to long. Lower pressure loads compared to high density loadings. And faster powders vs slow. (again a density issue)

And there are many theories on this running through my head. But there is a side note. All seating dies have some slop in them to accept / seat bullets larger in diameter. Some of the cowboy dies are really bad in this area. That plus the fact that belling dies usually allow more bell on one side of the case, for multiple reasons, and you are talking serious bullet run out after seating. The base of the bullet finally aligns when it reaches a portion (depth) NOT expanded (alignment ruined) by the beller.

Crimp centers the front of the bullet to restore alignment. In every test I have ever run, it has improved alignment by reducing bullet run out. The heavier the crimp, with heavy defined as that permitted by bullet design itself, the better alignment gets. In other words, you can have a bullet design where the crimp is inadequate to totally correct alignment itself and so that design will cause negative opinions on crimp to develop.

So is a crimp more accurate because of the aid in powder burn? Or does the real accuracy difference come from improved quality ammunition (alignment) and we just misdiagnose the result?

[38 Super Auto]

1. Do I need one of these "Carbide Factory Crimp Dies" for 380 ACP pistol and
38 Special revolver cast bullets?

I think the taper crimp die with your 380 die will work OK. Some reloaders like the Lee FCD for problem rounds or to increase feed reliability.

I'd recommend the Dillon case guage for your 380 ACP or any semi auto caliber. If your reloaded round chambers in this guage, it is just about guaranteed to chamber in your rig, unless you have a non standard chamber cut.

It's a good idea to remove the barrel from your rig and verify chamber fit with your rounds, before you load up too many.

There have been reports of FCDs that size the bullet down too much, so be aware of what the FCD is doing to your rounds and how it may affect your accuracy (and barrel leading)

I have several FCDs for semi auto rounds - I don't have any issues.

[Yance]

I bought the Lee FCD for .45 Colt since I don't resize the cases I use for Black Powder Cartridge matches. I simply thumb seat the bullets down to contact the compressed powder charge then run them into the FCD. Makes a beautiful roll crimp as light or heavy as you want.

SAAMI "MAX" specs?... Experimenting with some 330 and 340 grain booilts for .45-70 in .45 Colt cases and an inordinate amount of H-110...

Bullets were cast of 30-1 then sized and lubed in my .460 sizer. They chambered with no problem in my Rossi '92 but would not pass through the feed rails. Enter the FCD.

Thinking that the sizing capability of the die "should" size the bullet/case combo enough that it would feed I was surprised when they hung up in the rails again! Sizing the bullets to .458 allowed cartridges to feed as expected.

I can't be made to believe that the FCD can actually size a bullet "undersize" in a loaded cartridge.

[44man]

OK, I don't have the pistol die, just the rifle for the 45-70. I don't like it! It has to be used gently.
I don't like the idea of sizing a loaded round either unless it doesn't size down the boolit. I use too many oversize boolits. I also neck size a lot of revolver loads and don't want the base sized.
I can see where it would improve function in an auto though and for the speed loaders. Not my cup of tea for accuracy.

[44man]

Bass, that is why I like Hornady dies. The expander doesn't go in the case very far, just enough to start a boolit.
Some dies have expanders way longer then a seated boolit and ruin case tension. Even the Lyman "M" die expands too much.
The Redding profile crimp dies WILL size an oversize boolit so I have to juggle between it and the seating die depending on the gun I load for.
You are on the money about what the crimp does and doesn't do too.
The hardest thing do explain is just what crimp is needed for different boolits/bullets because all are different.
Take the factory crimp on .454 brass with a tough jacketed bullet. Brass is almost ruined. Put this crimp on a lead boolit and it will ruin the boolit size too.

[Bass Ackward]

Bass, that is why I like Hornady dies. The expander doesn't go in the case very far, just enough to start a boolit.


Jim,

Yes. But even they are not perfect. If you reach up with your fingers and hold the floating sleeve before the bullet enters, then hold it until you feel the case bottom out on the crimp angle, you get about .002 less run out than if you just raise the ram and let the die work like it is supposed to.

But let that crimp area foul up with lube and you actually increase run out. Another advantage of holding the stem is that you can feel any lube build up and clean your dies before you get a problem. But you have to do this or Hornady dies get worse the more shells you load.

[44man]

I admit to cleaning dies more then normal. Price we have to pay I guess. Lube can make a mess in any dies.

[ANeat]

I can't be made to believe that the FCD can actually size a bullet "undersize" in a loaded cartridge.

Its possible and ive seen it several times. One guys .357 mag bullets were going into the case @.358 He was having leading and accuracy problems and when pulling a bullet it was .357 He called Lee and they stated they had a +- .0008 tolerance on the carbide ring.

So if your brass may be a tad thick, or you run your bullets a little fat, or you have a die that is on the tight side of the tolerance you could have a situation where the bullet gets sized.

Its pretty easy to measure the ID of the carbide ring, measure your bullet and measure the brass thickness. You will find out if you have a situation where your bullets may be getting squeezed.

Or just run a dummy round thru the FCD, pull the bullet and see if its still the size it started at.

Rounds like 9mm that have a generous taper are usually OK. I have a 40S&W die that will size down a cast bullet but is good with a jacketed.

[Tiger]

Its possible and ive seen it several times. One guys .357 mag bullets were going into the case @.358 He was having leading and accuracy problems and when pulling a bullet it was .357 He called Lee and they stated they had a +- .0008 tolerance on the carbide ring.

So if your brass may be a tad thick, or you run your bullets a little fat, or you have a die that is on the tight side of the tolerance you could have a situation where the bullet gets sized.

Its pretty easy to measure the ID of the carbide ring, measure your bullet and measure the brass thickness. You will find out if you have a situation where your bullets may be getting squeezed.

Or just run a dummy round thru the FCD, pull the bullet and see if its still the size it started at.

Rounds like 9mm that have a generous taper are usually OK. I have a 40S&W die that will size down a cast bullet but is good with a jacketed.


ANeat

I believe if person fires a cartridge there is a difference in what the neck does to the bullet. If you pull a bullet out of the case without firing I think bullet size will be smaller then before seated. Some talk about the crimp sizing down bullet when fired as bullet is pushed out of case. I don't think so. I think gas expands neck and crimp. When you pull a bullet you are slowly pulling through the crimp. The bullet also get sized down some when seating depending on how hard alloy is.

Anyways I agree I don't like sound of this Lee FCD.

Ralf

[Mugs]

Love the Redding Profile Crimp die.
Mugs