Home Forums Hunting & Shooting Ask The Gunwriters Lee Factory Crimp Die

Do they improve accuracy, especially with slow burning powders in over-bore cartridges?

Looking for options.

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No idea on overbores, but I couldn't find any difference with 77gr SMKs over TAC in 5.56 loads.

I have no use for the rifle version of "factory crimp die"

But I have use for the pistol version of "factory crimp die"


Measuring many brands of 45acp carbide sizing dies, the carbide ring will have an inside diameter of 0.464"
Measuring a factory crimp 45acp die, the carbide ring will have an inside diameter of 0.469"

Per SAAMI a 45acp case has a diameter between 0.470 and 0.476".
So the factory crimp die can be used to make already handloaded ammo conform.

IF you try to size already handloaded 45acp ammo in 0.464" die, you are in for a struggle.

Always for pistol ammo. Never for rifle, except for maybe heavy recoiling lever guns. Used a crimp die with my 348win ammo. Always use them for my semi auto pistols. Makes it run like factory ammo. When I first started loading pistol ammo, I was having issues with failure to feed some of it in some of the tighter match chambers. After buying and using the LFCD, no more issues at all.. OP is vague. Don't know if he's asking about pistol or rifle ammo???? Likely rifle ammo, since he's asking about "slow" burning powder. Again, no need in most rifle ammo..

I use them in a number of rimmed handgun rounds and the 348 Win, 375 H&H and the 416 Rem.

I had read a lot of positive posts on another site about the 5.56 crimp die. I decided to try one and I purchased the Lee.

I took a very good load that shot well and loaded up some rounds finishing them off with the factory crimp die. I then shot it in a very tight shooting rifle. The groups opened up significantly.

To be sure it was not a fluke I took a second load and did the same thing. Those groups opened up.

I have not used the die since then.

I did a home brewed test with a weird unpopular cartridge, the .30-06, chrono'd 20 rds crimped, 20 rds neck fit...my velocity spreads almost dropped to half with the Lee FCD. So, guessing, I'd say somebody that doesn't want to fiddle with uniforming neck tension can make better loads with.

I have tested them on a few bullets. In a 308 win with the 150 SST, a light crimp improved accuracy and lowered SDs for me. On 168 bthps, the crimp did not make any significant changes.

Had some mixed results in 223, but nothing really significant.

I am not turning necks or sorting brass by weight/capacity, or any other fancy stuff.

I used to buy a Lee Crimp Die for every cartridge, but have stopped. I tested several different cartridges and decided that I would only crimp for compressed loads. I posted this a couple of years ago. This is for a 30-303, but the cartridge doesn't matter. I never saw an improvement with the 223, 308, 303 or the 6.5x55mm either.

100 Round Results
10 x 10 shot strings*

Uncrimped
1. 2.25 inches
2. 3.60 inches
3. 1.75 inches
4. 2.55 inches
5. 1.60 inches

Crimped
1. 2.50 inches
2. 3.00 inches
3. 3.90 inches
4. 2.90 inches
5. 3.00 inches

*The measurements were rounded off to the closest 0.05 of an inch.
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Average group size for 50 shots

Uncrimped - 2.35 inches
Crimped - 3.06 inches

Average velocity for 50 shots
Uncrimped - 2708 fps
Crimped - 2703 fps

Here were the last two 10 shot groups fired. - Uncrimped (left) Crimped (right)



I believe crimping might help if you have cases that have never been annealed and are beginning to harden. The window for this would be small however, as crimping does nothing to stop case hardening. If anything, it might hasten cracking around the case mouth with cartridges that are about done.

This is generally where I've found the crimp die sometimes helps. If used with consistent pressure, they tend to even-out neck tension, which helps release bullets from the case consistently during firing. If not used with consistent pressure, they don't....

I have 6 different Lee FCDs. I used them mainly for loading Hammer bullets because that is what they recommended. Most of the Hammer users seem to follow that advice. However, after experimenting for over a year with the FCD, I determined that the benefits or detriments could not be pre-determined. Some loads showed less consistent velocities and were less accurate, while others displayed a distinct improvement with lower SDs and smaller groups at distance.

The FCD is cheap enough that it's certainly worth a try even if you aren't shooting Hammer bullets. I've got far more expensive reloading equipment sitting idle on the shelf.

It makes a nicer looking finished round.

And, when loading the 416 Rem for my bud's Africa trip, I do a Factory Crimp on those rounds. Not that a bullet would back out of the case during recoil, I for sure know they won't when I get done with them.

DF

How does the Lee FCD effect bullet runout in rifle cartridges?

Any time you add a die to the assembly process, it's possible that runout can be introduced. With the Lee Crimp Die, I have not noticed any change in runout however. I know several people who had problems with the LCD, but that was usually the result of not cleaning the die before its first use.

This bit of metal will stop an even pressure application on the neck, and could be a problem.

I use them for lever gun loads.

I am a big fan of them. I just finished loading some 9.3x74r using RCBS dies and hate all the steps to seat, crimp, final setup to repeat. I much prefer to do each operation with a single die. Unfortunately Lee doesn’t make dies for that caliber.

I use them for all pistol ammo I load and all lever gun ammo. I also have one load for one particular rifle that I crimp with a Lee factory crimp die. A Ruger 300 Win mag with the typical short magazine and longish throat. I found much lower ES and really good accuracy after crimping a 180 interlock on top of a mostly full case of ramshot magnum. The rifle has some sentimental meaning to me otherwise I wouldn’t go through the trouble.

I like them. I’ve usually always seen at least somewhat of a gain in accuracy sometimes a lot when using them and even when I haven’t it didn’t hurt accuracy either.

30-30 is the only rifle round that I crimp. It is the only bottleneck chambering that I have that gets run through a tube mag.

For pistol rounds, I have a Lee Factory Crimp Die for each chambering. I find it does a fine job of uniforming the rounds.

That’s kind of where I’m at. Just beginning with loading .30-30, and the Lee die is supposed to work as long as the cases are within min/max limits, as opposed to all being the same length. Just read Brian Pearce’s loading notes on that last night. Sounds good to me, as in easy, as I’m not worried about wringing out the last little bit, of anything really, out of the old Marlin I just got.

I appreciate the economy and convenience of the FC die included in the handgun dies. It’s often recommended to seat and crimp separately, and the extra die saves time and money.

Once or twice I’ve used the crimp feature on a regular Lee Loader to “correct” the odd round that didn’t have quite enough neck tension, probably not an “accuracy” technique, but works in a pinch.