Cartridge OAL Variation ~ ABL Pro

[DocHolliday]

Being new to a progressive press and specifically the Lee ABL Pro, I have a question.
I have run about 100 dummy rounds (no powder/primers) through it so far. The case feeder is working fine. The dies are dialed in for my specs.
After measuring, I am seeing a variance in CAOL of 1.126-1.136. Both ends are well within my load data specs. Is this acceptable or is there something else I should look at?
I'm loading 9mm range brass. All of it has been deprimed, cleaned and bulge busted. 124gr plated projectiles. TIA.

[Ranch Dog]

That seems like a lot to me. How well does the bullet seating plug match the nose profile of the bullet?

Lee has a pretty good FAQ that covers all the aspects of COAL variation: http://leeprecision.net/support/index.p ... -variation

[DocHolliday]

I’m using 124gr FP plated bullets by Accura Outdoors.
I ran 5 series of 12 each and found the last one in the series is an outlier being too short. I guess this makes sense with the plate not completely loaded.
The best I have achieved following the links instructions is a variance of .006.
I tried applying ink to the bullet to check the seating plug fit but did not have much luck. I cannot give a good answer to that question.

[EdgeOfEden]

DocHolliday: I hope you've had a chance to review the link that Ranch Dog provided you. It's excellent information.

If you suspect the variation in bullet shape or ogive variation may be a problem you can also remove the seating stem and place it on thirty plus bullets and measure each respectively with calipers from the base of the bullet to the top of the seating stem. I did this once and found .007 variation among the bullets. This accounted for much of my COL variation. In my case it was Nosler 44 mag 240 grain jacketed soft points, which are notorious for this.

Bear in mind that even expensive bullets can have variation. Only a long range match shooter might worry about this and he would likely sort his bullets. For the vast majority of us, if it fits it shoots.

The other thing I like to do on a progressive press is preload the plate. If you setup your press by running a single case around the shell plate to make all your die adjustments then when you actually start reloading as the plate fills up it flexes differently and will cause a variation in your COL. I like to load the plate up full as I'm making my final die adjustments. This minimizes the effects of shell plate flex and should give more consistent results. However, the first few on and the last few off will likely be different in COL from the main run.

One final thought: While the ABLPro uses only a 4 station shell plate and is therefore smaller and should be subject to less flex, it is certainly not immune.

Hoping this helps.

[Ranch Dog]

I took the liberty of splitting this into a stand-alone topic; someone else will need the information down the road.

After the bullet plus seating plug measurements, I suspect that it is going to be the bullets ogive variation. A comparator might identify this further, but they are generally used with rifle cartridges and pointy bullets.

Another thought I had as I reread your original post, was what I found through experience during the setup on my Load-Masters; only use cases that enter the press from the first station. Don't recycle a case through the same station without starting it back through all the previous stations. In the case of bullet sizing on the ABLP, each case would be sized and expanded only one time. I found myself running cases through the expander (powder drop cycle) twice without resizing, and this resulted in bullets being seated deeper than the previous cycle because the flair on a previously flared case would open up further and the bullet meets less resistance on each additional seating. Case neck tension or the lack of it is a real thing and can cause .003+ variations during seating.

You might not be using an Auto Drum measure, but the above is key to setting up this delivery system as well. Every test drop must be from a freshly sized case.

[EdgeOfEden]

I smell another topic split

My sense of smell is not that great, but I did sense the same thing coming.

[DocHolliday]

So I think I got it figured out. I reinstalled the Drum after reading the comments and it’s working great. No leaks. I prefer the fine tuning capability.
Regarding the CAOL, I have it down to 1.130-1.135 and I’m aiming for 1.132 so I’m satisfied with that. The thing to do, at least in my hands is to preload the shell plate and finish with it loaded also. In other words , I have a few empty cases to start and when I finish. This has seemed to settle it in for me. YMMV.
Thanks to all for the advise. It saved a lot of trial and error.

[EdgeOfEden]

That's great news, DocHolliday!

[Ranch Dog]

I smell another topic split

My sense of smell is not that great, but I did sense the same thing coming.

Auto Drum stuff split out as best as I could: https://lee-loader.com/viewtopic.php?f=20&t=2502