OAL variance

1
So a friend and I are getting her press set up. Everything has been going fine. Some things took a while to get fixed, other things were easy. But we have hit a snag. We get the dies all set, pump out a few rounds and measure the overall length. The recommended overall length is 1.08 +- .02. Here's the problem. The OAL is varying between 1.06 and 1.14. We readjust the seating die and try again. Same thing happens again. Does anyone have any idea what we need to do???????

We are reloading once fired 9mm brass with coated bullets from Missouri Bullet co. The press is a Dylon 650.
Any help or advice would be greatly appreciated.
Last edited by Hiker on Fri Aug 31, 2018 8:30 pm, edited 1 time in total.
All religions united with government are more or less inimical to liberty. All, separated from government, are compatible with liberty.-Henry Clay
Both oligarch and tyrant mistrust the people, and therefore deprive them of their arms.—Aristotle

Re: OAL variance

6
I found this on the Dillon site.
https://www.dillonprecision.com/kb/arti ... l-variance
If you are experiencing a greater than normal variance in your Case Overall Length (COL) you may want to check your projectiles for variances in the ogive. It is likely that most of the variation you are seeing is caused by variations in the ogive of the projectile. To test:

pull the clip off the seat die, push out the cross pin and remove the bullet seating stem.
Hold a projectile up into the stem, and measure from the base of the projectile to the top of the bullet seating stem.
Measure 50 or so, and see what the extreme spread is.
For testing we measured 100 traditional 9mm 115gr fmj rn projectiles, from a well-known manufacturer, and found .026" total variation.
My friend and I will be looking at this to see if it might be the problem. Thanks eelj for suggesting the Dillon tech support. They have a database of various issue that you can search. I hope this works.
All religions united with government are more or less inimical to liberty. All, separated from government, are compatible with liberty.-Henry Clay
Both oligarch and tyrant mistrust the people, and therefore deprive them of their arms.—Aristotle

Re: OAL variance

7
I'm not familiar with the bullet supplier. You might check the bullets for a uniform coating and size. Also what are you measuring the ammo with? Is it a dial caliper or a cheap electric one that might have old and weak batteries. My Dillon is a Square Deal and the tool head is bolted on to the press, I believe the 650 much like the 550 has tool heads that slide in and then held in with pins. Are you using a seating plug that matches the bullet profile?

When I typed this you had not responded, glad I checked before submitting. When you say coated bullets I imagine they have powder coating on them. The thickness could theoretically vary.

Re: OAL variance

8
By the way Hiker when you guys get this all figured out more than likely you will reassess what buying in bulk is all about. Especially ammo boxes for storing ammo in. I like 3lb plastic coffee cans, shoe boxes are the correct dimension but are not quite robust enough to hold a full load.

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