Over crimpng

[volshooter]

Some how my last 2 test batches of 9mm shot lousy wth proven recipes. Turns out my taper crimp had ben set to harsh. My fault for sure. Over crimped 9mm loads will not shoot good groups. Readjusted die and loads are back to normal.
Perhaps the roll crimp on other rounds, that require it, had something to do with my adjustment. Back in business.

 

[Jimbo357mag]

That's interesting.

 

[Jim Puke]

Remember, you don't need to roll crimp jacketed 9 mm...only slight taper crimp. Also, be careful of over crimping cast bullets as it can lead to over pressure because the round will go too deep in chamber...light crimp maintains proper headspace on rimless cartridges that headspace on the case mouth. Bullet seating depth and crimp are important things to monitor on high pressure rounds like 9mm.

 

[Rick Courtright]

Hi,

I've used the Lee FCD (factory crimp die) on my 9mm since about the second box of 9mm I ever loaded. Lee claims it's impossible to overcrimp an auto case with the taper crimp it applies. While the roll crimp versions of the FCD CAN be set for pretty severe crimps, I've yet to over do it with the taper crimp version, so maybe they're onto something! It's easy enough to set from min to max to satisfy most anybody's wants or needs and cheap enough it won't break the bank if one doesn't like it.

Even if one doesn't like the Lee brand (sit quietly, 6gun!), or doesn't want to go with the Redding Profile Die to do the same job, it's easy enough to use a "4 die approach" with their regular seating/crimping die, seating in one step, coming back and crimping in another. It might be worth a shot to try...

Rick C

 

[volshooter]

I am using a LEE taper crimp die. While LEE claims seating dies made in recent years have the taper crimp, I still prefer to have a separate taper crimp only die at the end. I will disagree with LEE on their dies ability to over crimp, and I'm a big fan of theirs.
I use a factory round to set my dies with, but I reckon I must have tightened it down another bit last time. It made a serious difference in groups, especially with the powder coated lipstick bullets. I know that the 9mm does not need to be crimped, but I just need to reform the opening of the case mouth that was applied to accept projectile. My fault. I have only been reloading 9mm for a few years. I load quite a few .45LC, .44mag, .44spc and .38/357, all that need roll crimp as well as tons of .45ACP that my dies are "set for". So extra pressure when crimping is normal for me. I actually have a 45acp barrel that has a good cut away to check for proper fit. An old feller, who shot at places like Camp Perry gave it to me when he sold out. Yeah, I bought everything he had and his recipe works. The set screw on RCBS dies prevents getting the out of adjustment once adjusted.

My last test rounds were with 115gr powder coated 9mm and 95gr Federal soft points, using Unique vs. Bullseye.
Best loads were
115gr lead powder coated 4gr of Bullseye beat 6gr of Unique.
95gr SP shot better wth 5gr of Bullseye than 6gr of Unique.
All loads shot great groups but the Bull did better shooting from a very good sand bag rest @ 21 feet and all wth the same pistol. Target was a small sticky note perhaps 1 x 2 inches.
Very pleased wth the test rounds just some better than others.
For both bullet weights tested Bulleyse produced better groups good thing cause
thats it's a staple in my supply.
BTW the hard taper crimped rounds left over were fired they are the same bullets and powder charge as the light crimped, huge difference in grouping.

 

[loaded round]

I use Dillon, and some Redding dies on my various semi autos and they all have taper crimps. Didn't check any of my revolver dies since I don't shoot many wheel guns these days.

 

[Ka6otm]

When using powder coated bullets, I use a powder coated bullet to set the level of "ironing out" of the flare as all the powder coated bullets I've bought have been slightly larger in diameter than jacketed or plated bullets

 

[mikld]

FWIW; Yep, you can over crimp with a Lee FCD. It will over crimp and bulge cases, but, the carbide ring just brings the bulges down to SAAMI case diameter...

I'm one of those that don't crimp any of my semi-auto rounds, I just remove any flare with a taper crimp die, aka "De-flaring"... :lol:

 

[Rook]

I wish I was a good enough shot to where the crimp made a difference on my "groups".

 

[Kevin]

I don't apply any more crimp than absolutely necessary. In most situations there isn't very much crimp needed.

Like mikld said, more of a de-flaring, than actual crimp.

 

[sliclee]

That kind of crimp is called a "KISS" Lee

 

[mikld]

I'm one of those that don't "crimp" any of my semi-auto loads, in the true sense of the word. I just use a taper crimp die to straighten out any flare in the case mouth and use the "Plunk Test". Been doing it this way for a long time for 2, 45 ACPs and 3, 9mms.

 

[Rodfac]

I'm one of those that don't "crimp" any of my semi-auto loads, in the true sense of the word. I just use a taper crimp die to straighten out any flare in the case mouth and use the "Plunk Test".

Yep.....good advice this. For those that doubt...try an accuracy comparison, shooting off bags...it'll make a believer of you. Rod

 

[volshooter]

100% my fault. It is indeed possible to overcrimp even with a taper crimp die.
Honestly, I have a medical condition that distorts my normal muscle pressure. The nerves fire/twitch so fast that I do cannot drink from aluminum cans, as I end up crushing/distorting them. Hand shaking is a real problem. Basically, the muscles stay semi-rigid. Kind of like involuntary isometrics. Folks who hug me usually ask "why so tense".
But yeah, neck tension is all that is needed and the removal of the flaring. It does make a huge difference since over crimping deforms the bullet. Not a good thing.