Why Would Cartridge Lengths Vary By .010?


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parker51
January 8, 2013, 03:01 PM
Been reloading for close to 25 years and I may just be having a senior moment, by why would this batch of .223 cartridges vary by .010? I am using the same lot of Speer FMJ bullets and the brass is FC trimmed to 1.750. I've had some other reloads vary slightly, but never noticed any this bad. I set up the seating die to seat the first bullet in the center of the cannelure with no crimp. The first 4 were spot on, then I noticed that the 5th bullet was seated below the cannelure. Am I missing something?

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rcmodel
January 8, 2013, 03:12 PM
Variation in bullet tip length.

Not every bullet in your box came out of the same forming die.
So there are minor variations.

You are seating from a place on the bullet ogive, and measuring from the tip of the bullet.

If you use a bullet comparator to measure OAL that allows you to measure off the same spot on the ogive the seating stem pushes on, they would very likely all measure the same.

http://www.brownells.com/reloading/measuring-tools/bullet-comparators/sinclair-bullet-comparator-1-sku749002942-34262-66673.aspx?utm_medium=shoppingengine&utm_source=nextag&mc_id=11000&gdftrk=gdfV21820_a_7c187_a_7c747_a_7c749002942_d_749002942_d_20531

rc

parker51
January 8, 2013, 03:37 PM
RC,

I appreciate the help. I didn't really know how the bullets were made, guess I figured they would be more uniform than these. I don't normally use bullets with cannelures as I don't crimp most of my rifle reloads, so these looked a bit odd with some of the cannelures not seating as deep as the others. I wasn't really worried about these bullets hitting the lands, but was concerned there might be a problem with my press since some of the loads I use for my hunting rifles have the bullets seated .020 off the lands. I see now that the extra length of these bullets would not cause the bullet to hit the lands even though they might be somewhat longer than others. Thanks again for your help.

gamestalker
January 8, 2013, 03:47 PM
What RC said. Also, as material builds up on the seating stem it will add to those variations.
I first noticed what you are seeing many years ago, and I thought it was something I was doing until my buddy pulled out his comparator and showed me.

GS

Still Shooting
January 8, 2013, 04:10 PM
Great! A new guage to buy...or maybe two. The first has every diameter I load regularly from .224, .243, .257, 6.5, and 308, with one exception. I'll have to buy the second one as well, for the .270.

It's a good thing my wife has no idea how much I spend on reloading. I think she just ignores it, because she likes to shoot, and because when I'm home reloading, on the range (with her), or hunting (with her), she knows I'm NOT out there chasing some other woman...

rcmodel
January 8, 2013, 04:13 PM
If you are handy, you can make them with a drill press, a set of #drills, and a couple of big hex-nuts!

rc

moonzapa
January 8, 2013, 10:41 PM
I ran into this phenomena not long ago. I don't use the cannelure for seating my bullets, I don't have a lever operated rifle, etc. However, I noticed the variance in the perceived lengths of my reloads. Ensure that all of your brass has been trimmed equally, to the same length.

If after trimming and verifyings your brass lengths to be the same and you still miss the cannelure, I would suspect the ogive of your bullets are varying. As a general rule of thumb with me, I measure all of my bullets and cull out bullets that vary more than .003". I use Hornady's bullet comparator in conjunction with my digital caliper to do this task. It works well. It all comes down to how precise do you want to be? I'm a perfectionist and want to squeeze out the nth of accuracy out of all my hunting loads. To each his own. Hope this helps out.:)

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