Over crimping causing tumbling ???

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shortround

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I have just reloaded a new batch of .45 230gr truncated round nose , after taking them to the range I notice I am getting more keyholes than roundholes . one major difference is that I added using a Factory Crimp Die for use in my S&W 625 ,

Is it possible that I over crimped and made the bullets too small for the barrel diameter ? Just a thought and I welcome any other opinions that can help me fly right

THX
Shorty
 
That would be my first guess.

When using the Lee FCD you aren't supposed to put much crimp at all, and I would argue that you should not be crimping, but just getting all the belling out of the case.

In a semi auto(not sure in the revolver) .45 acp head spaces on the case mouth so you need to be careful with crimping. Even in the revolver the loads aren't hot enough to make the other bullets jump like they might in a magnum cartridge, so heavy crimp isn't necessary.

Really it shouldn't be necessary to hold the bullets in place at all, for me it was more for reliability in feeding.
 
Sounds like an overcrimp as well. Just remember that you need to adjust the crimp to the gun.

In my 1911 (9mm) I have to use a full turn of the FCD in order to get the pistol to feed properly. With my 4506 I use a very light crimp.

I started with a light, light crimp on a dummy bullet (no primer or powder), measured the overall length and loaded into the pistol from the magazine. Eject and try again. Measure the overall length of the bullet. If you measure noticeable setback then make another and add more crimp. Do this until you get what you believe is acceptable setback or non. That is how I tailored each bullet to my specific pistol.

My $0.02

Later....
 
Are these cast bullets? The carbide sizing insert in the Factory Crimp dies could be causing the bullets to be undersized because brass is springier than lead. If you pull a bullet from a loaded round, is it smaller in diameter than a bullet that hasn't been loaded?

Otherwise, it is also possible that you are crimping to the point where the bullets are being excessively deformed. What is the diameter of the crimped case mouth? It should be around .468"-.471".
 
Did you increase or decrease, or change the powder charge?

Was the use of the FCD the only difference from your previous procedure?

Did you change your lead alloy, or mold?

Did you resize to the same diameter as before?

Did you use the same lube?
 
Thanks Everyone,

Let me try to answer your questions and narrow down this annoyance.
Jawsman: AS I said I am using this in a revolver so the OAL isn't as critical as an auto but I will check if there is a difference between the bullet seating die and FCD on my 55o.

tjhaile : yes these are cast bullets and I have used them before

easyrider604 : these are the same bullets we have been using for a while . These bullets were't resized before use and yes the FCD is my only change.

mletovaara : Yes the barrel was cleaned ,as it happens I did a full strip down and thorough cleaning .

I will check out your suggestions and check back


Shorty
 
Hey Guys,

I finally got a chance to get around to measuring the rounds that were giving me trouble with accuracy . The cses at the mouth measured within the posted limits . However when I took the calipers to the cast bullets themselves they were well below what is required , they were only between .440 and .442 . No wonder they were tumbling . I never realized that the FCD would compress the bullet that much . I guess that I will have to unload the rounds that I loaded in that batch and reuse the brass and the compressed bullets will go back into the melting pot for a second try . Backing the FCD will have to be backed out and remeasured a bit more accurately this time .

Thanks for the help

Shorty
 
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