C O A L

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bradford

Bearcat
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I use a Dillon square deal for reloading. I have been checking the OAL of my .40 (1.135)
I keep getting different OAL's by about +/- .006. Mostly on the higher end and most are only +.002. Is this pretty normal? I read where seating them too far is more dangerous because it develops higher pressures. Is this not enough to be concerned about?
 

Jeff H

Bearcat
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Cincinnati, OH
Wellllllll, the thickness of a human hair averages around .004. If that type of thickness is really important to you, you are more anal than I.


Being really new at the whole reloading thing, I will bow to the greater wisdom of others, but it does seem like a rather trivial length to be worried about.
 

slippingaway

Blackhawk
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More than likely, that difference in OAL is being caused by irregularities in the "point" of the bullet. The seating die usually doesn't contact the exact point of the bullet, but contacts a portion along the ogive. I wouldn't worry if it's only a few thousandths.
 

J Miller

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bradford,

I used to fret over differences in the COAL of my hand loads until I measured a box of factory ammo.
I found my hand loads, even with their variations, were far more consistent than the factory ammo.

I quit worrying about it.

Joe
 

contender

Ruger Guru
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Is that .006 or .06?
A .06 is a lot more than .006.
In a 40 cal,, it can have a bit of an effect if it's .06. Not a huge amount, but some.
Next, it could be due to many different things. Brands of brass, bullet construction, primer height, lead bullets seem to accumilate extra lube in seaters, etc.
All this just raises more questions.
 

bradford

Bearcat
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Thanks for all the input. The headstamps are all different. It shouldnt make any diff. in the OAL though. I do see your point about how deep the bullet will be seated in a longer shell. I am talking about .006 and I am reading here that that seems like not enough to be concerned about.
 

Rick Courtright

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Hi,

I prefer loading bullets that are cannelured, because I figure as long as the mouth of the case crimps "somewhere" in that cannelure, I'm ok. That gives me somewhere around a 0.010" window w/ my favorites.

Now, just to explore what COAL is all about anyway, you've gotta look at your data and you MAY find some of it shows "minimum" while others show "maximum" figures. It's the "minimum" ones I pay attention to, because they're derived based on the volume of the case and attendant pressure situations. The "maximum" is often there to ensure your loaded round will chamber, fit your magazine and/or feed properly.

Back to the cannelured bullets, they also eliminate much of the need for expensive "measure at the ogive" gauges. The distance from the base to the cannelure is pretty much a constant, while the tips of certain bullets can get bashed, smashed and squished all over, making truly accurate measurements difficult to take, anyway!

Rick C
 

contender

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What Rick says is true, except that in reloading ammo that headspaces on the case mouth, a taper crimp should be used. A roll crimp can cause feeding issues.
 

Rick Courtright

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contender":unujtn9w said:
What Rick says is true, except that in reloading ammo that headspaces on the case mouth, a taper crimp should be used. A roll crimp can cause feeding issues.

Hi,

So true!

And, since it's not likely one's gonna find a cannelured bullet for a caliber that headspaces on the case mouth, a little work w/ a caliper, calculator and a Magic Marker can be helpful, especially if one sets up "dummy" rounds for comparison.

It's nice to have a factory round to measure and disassemble, though not mandatory. I'm sure as w/ most things reloading related, there are several ways to set things up, but I use this formula when I have to "wing it":

Nominal case length plus total bullet length minus COAL (from the book or measured) = length of bullet seated inside the case.

Then I measure that length from the base on one of my "unknown" bullets, mark it w/ the Magic Marker, and make up my "dummy."

It seems to work ok... and I'm not surprised that despite the COAL variances in the books, the amount of bullet inside the case remains reasonably constant. (The same formula works when using non-cannelured bullets in cartridges that don't headspace on the mouth, like a lot of rifle bullets, too.)

Rick C
 

slippingaway

Blackhawk
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Rick Courtright":1m6qdlh8 said:
Hi,

The distance from the base to the cannelure is pretty much a constant, while the tips of certain bullets can get bashed, smashed and squished all over, making truly accurate measurements difficult to take, anyway!

Rick C

Unless you get some like the Armscor 62gr .223 bullets I just got. Some of the cannelures are so far off that they are completely out of the case mouth when seated.
 

Rick Courtright

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slippingaway":y2chbz8c said:
Unless you get some like the Armscor 62gr .223 bullets I just got. Some of the cannelures are so far off that they are completely out of the case mouth when seated.

Hi,

Definitely NOT good!

This is w/ even length cases, I assume? (I'm not being a smart arse: once upon a time I had a similar experience that led to some serious case length measuring and a "learning moment" about my own QC practices! :oops: ) Have you talked to Armscor about the problem? Considering my limited experience has always been favorable w/ the mfrs I've used, I'd be wondering out loud if something got slipped up at the factory...

Rick C
 

slippingaway

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Yes, these are loads I'm trying to work up for accuracy. All R-P cases, trimmed to the same length. I took one of the bad bullets and a good one, and set them on the table next to each other, and the bottom of one cannelure almost matched the top of the second. So far, out of over 100 bullets I've used, only 1 was that bad. The rest were all pretty close. I just tossed the ones that were noticeably off into the "plinking" pile, and kept the best ones for testing.
 
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