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Old April 27, 2013, 03:40 PM   #1
MarkGlazer
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Inconsistent Bullet Size Question

Board, I need some valuable input.

I was loading 9mm last night and kept coming up with an inconsistent OAL. I am loading for a CZ 75 P-01. The chamber size is a bit tight so the max length can only be 1.068. The OAL kept changing on my rounds, sometimes right on the money but most of the time very much under the 1.068 max.

I thought it through knowing that I made no changes to the die, had tested the first round and came to the conclusion that the bullet size must be changing. [I consistently check the size of the rounds, as a beginner, it's a Quality Control thing for me.] Sure enough, I began to measure the bullets from the box, lead cast, 115 grain, and the size from base to nose fluctuated from .530 to .541.

I am currently loading using the mean grain of 4.1 (Hodgons Titegroup) Here is the question; if I set the OAL using the largest of the bullets and do not adjust the die, allowing the bullets to seat shorter, hopefully not changing the depth of the seating, do I face any danger on the firing line? My intent is to seat each bullet no further than the top of the blue line.

I do understand that I will not have a consistent weight. I do not believe that adjusting the grains as a compensating factor is a wise choice, rather keeping the median constant is the safe move.

Please advise your thoughts on this problem.

Thank you.
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Old April 27, 2013, 04:04 PM   #2
Misssissippi Dave
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I have a few questions. What press are you using? What bullet are you using? Which dies? These things would be very helpful to determine what might be causing your OAL to change. Some presses will be more accurate on OAL than others. The seating die used can cause this for certain bullet profiles. Just how much of a variation are you getting?
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Old April 27, 2013, 04:31 PM   #3
LE-28
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Also, does the bullet's nose profile match the profile of the seating stem in the bullet seating die? It could be deforming the nose of the bullet making the OAL vary. How soft are these bullets.

A loading press will make the length of the finished round the same everytime reguardless of the bullets varying in length unless something is deforming the nose.
Other than that, same questions Mississippi Dave is asking.
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Old April 27, 2013, 04:53 PM   #4
MarkGlazer
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I am using a Lee Single Stage press.
I am only using the Seating die, not the crimp die.
The variation in OAL can be anything from 1.068 to 1.06
The Brinell value is 18
Observing the rounds that I have completed, they are not changing in dimension/shape. I have compared them to those I have yet used.
I would rather not say from whom I purchased the bullets as I don't wish to disparage the vendor. I have sent the vendor a query but have not yet heard back from him.

I greatly appreciate your help. Thank you.
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Old April 27, 2013, 05:07 PM   #5
Dave P
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"The variation in OAL can be anything from 1.068 to 1.06"

Mark, 8 mils will change nothing. Its not rocket science. Load and shoot, and find something else to worry about. Like internet taxes ...
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Old April 27, 2013, 05:16 PM   #6
MarkGlazer
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OUTSTANDING.

Thank you.
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Old April 27, 2013, 06:42 PM   #7
UtopiaTexasG19
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Take the seating pin out of your seating die and see which end you are using. One end is usually flat and the other end cone shaped to basically fit the profile of the bullet.
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Old April 27, 2013, 07:16 PM   #8
flyguy958
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.008" is negligible. Go shoot!
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Old April 27, 2013, 10:16 PM   #9
Misssissippi Dave
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The variation is rather small. I too think checking the seater plug to make certain the part in there comes as close as possible to the shape of the bullet. When loading lead bullets you will find you do have to occasionally remove the plug in the seater die to clean it. Bullet lube etc can build up and change the depth you are seating. This doesn't happen much with jacketed and plated bullets. A few thousands of an inch probably won't make any difference you will see on paper with pistol ammo. It also helps to make certain you are pulling the handle the full lenth each time. I would guess you are doing this already.

I do suggest you crimp the rounds before shooting them. This will at least remove the bell you placed on the case to seat the bullet. It also helps to keep the bullet from moving when they are in the gun waiting to be shot.
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