Is it normal to get varying OAL?

[mikeinctown]

Just starting out with my 650 and I ran some test bullets today in 3 different charges. When I set and tightened the bullet seat die and measured the case I got 1.251 on a .45. Tested it in my barrel and all is good. (made one without primer and powder, then ran it through the magazine a dozen times to see how it would chamber at the 1.251 length) Ran a couple test bullets then and measured OAL and got between 1.251-1.253. Then I finished my run and after measuring every single one I made, I had a variation of between 1.251 and 1.256. I was very deliberate on the handle as I wanted to make sure I had appropriate powder and primer set correctly before I seated the bullet.

Is it normal to see a .005 variation like this with the press and Dillon dies?

If it matters I was doing the test with Blue Bullets. I have a batch of FMJ that I am also going to test once I get some feedback from the batch today.

<edit> Now that I'm thinking about it, .005 is next to nothing, but I didn't want to risk finding out that it should be almost exact each time.

Edited October 4, 2014 by mikeinctown

[Hi-Power Jack]

In my experience, that range is completely normal.

[Youngeyes]

They're fine. Shootem'.

[b1gcountry]

Yes, i typically try to go for a range of 1.135-1.140. Depending on how i measure them, I seem to get a couple that fall a little outside that, even. This is for forty flat point with lee dies. I have separated by exact oal before, and crono'd them separately. The results were within my sd.

[kneelingatlas]

The OAL varys because you're measuring to the tip of the bullet, but you seating die touches the shoulder, so inconsistencies in the ogive of the bullet are what give you the variation.

[WZ4I]

The OAL varys because you're measuring to the tip of the bullet, but you seating die touches the shoulder, so inconsistencies in the ogive of the bullet are what give you the variation.

+1

[Steve RA]

If you want to really tell, get one of the rifle set ups where it measures off the ogive of the bullet and not the tip. The tips can be deformed where the same spot on the ogive will be consistent.

[JoshRobillard]

+/- .003 from my target OAL is fairly typical for me.

[rdinga]

Take a couple of boxes of factory ammo and measure the OAL. Your variances are well within spec.

[buckaroo45]

Don't forget the common wisdom of having a case in all stations of the press. The variations should decrease.

[lucky13bullets]

The OAL varys because you're measuring to the tip of the bullet, but you seating die touches the shoulder, so inconsistencies in the ogive of the bullet are what give you the variation.

This ^^^^

measure your bullets before you seat them, you will see the same variances in them that you do in the loaded ammo

[b1gcountry]

Also the reason different bullet profiles will seat to different lengths at the same seater die setting.

[Mespo]

Perfectly normal.....

[mikeinctown]

Just wanted to give an update since I was the one who started the thread. I found that I was almost always .005 on the + side while I had cases in every station but that when I was doing one round as a test that the variance was almost zero. My guess is that the sizing/decapping station and the force needed to size the case tilts the shellplate or platform ever so slightly.

I believe I've been able to confirm my guesses as on my last loading session, the cases were lubricated slightly with One Shot lubricant. I did not give them a thick coating, but rather just quick sprays and then a mix in a bag. Not all sides were covered but I believe that they would have evened things out as they rotated through the die. In any event, the 650 operated much, much smoother and with far less effort than needed before the lubricant. After finishing the session and measuring the finished length, I found a variation of only .002-.003 in most cases. This leads me to conclude that the reduced force needed on one side of the platform affects the OAL to the positive in terms of reduced variation.

[phecksel]

I was seeing a greater variation on brand new brass and ran the complete round through the seating station again.

I'll try lube next time.

After running each round through again, ended up with .002 variation. Am I causing any other issues by doing this?

[accu9]

That's totally normal and safe. Variations in the; bullet, thickness of the blue coating and brass will produce minor OAL variations like you are experiencing. Blast away!

[Kaskillo]

.005 not too bad but I shoot for .003