Question on OVL variation

T

tedbeau

New member
just starting to reload and I am finding that I am not getting a real consistent overall length. In a batch of 50 rounds I vary about .008 to .010 total.

I am loading 40 Caliber using mixed brass, I initially attempted to set up for an overall length of 1.125 because that's what the load I was referencing was set for. Some bullets ended up short by .005 or .007. Some ended up long by .003 or .005.
I am loading on a Hornady AP progressive using Hornady dies and Berry plated 180 RNFP. I didn't sort the cases by headstamp so that may account for some of the difference.

So the real question is what is a normal variation in a batch of reloads?

These are practice/IDPA loads that I want to be low recoil. I'm not as concerned about accuracy. Just want some that make the minimum power factor and feed OK and are safe.

I did finish up the box of Berry's and loaded some XTREME Bullets. After I adjusted the seating die I seemed to get less variation with the Xtreme bullets. Still getting an overall total variation of about .006 to .008.

Is that normal?
 
I think that this is a very good subject for a thread for newbs.

What would experienced reloaders consider as being normal variation ?
 
0.002 inches would be my total when loading 180 grain Berry's on a single stage Rock Chucked. Seat and crimp in separate steps.
 
I separated the seat and crimp on my RCBS progressive, and the
overall length variation went down to almost nothing.
 
I do seat and crimp in different stations. I bought a separate taper crimp die.
I am thinking I need to reset my crimp part of the bullet seater die. maybe back the crmp body off a half a turn and then reset the bullet seater stop. Also as I said I did not sort the case by headstamp/manufacturer or check and sort case lengths but in thinking about the press operation the case should not effect the overall length because the distance from the bottom of shell plate to face of bullet seater face should always be the same.

The die set came with two different bullet seater tools. One is a cone (what I have in there) and one is a flat face. If the bullet ogive is varying I can see where the flat seater tool might be more constant in overall length.

I do understand that its the distance to the ogive and the start of rifling in chamber that really matters, but that's not what an overall distance check is really measuring.

For instance check out this post about differences in a "lot of 1000" bullets.
http://thefiringline.com/forums/showpost.php?p=6056658&postcount=96

SO should I be using the flat face seater tool?
 
Use the seating profile which most closely matches the bullet profile. I can't determine if you are using round nose or flat point bullets. Berry's doesn't list the type you stated you were using.
 
Overall cartridge length is only a real concern with hot loads.
With the mild ones like yours, as long as the rounds operate in the magazine and feed well, then not to worry.
And, since you have a power factor to meet, no doubt you are using a chronograph.
It will tell if the loads are as expected.
 
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