Another COL Variance Question

T

Tony C

New member
I know this is another C.O.L. question, but this one has me a little concerned.

For seven years I have been using a Hornady Classic single-stage press for my reloading. Recently I've "upgraded" to the Hornady LNL AP progressive press, which has been a bigger transition than I thought it would.

My concern revolves around bullet seating. When I am setting the press up for use, (I've been loading about 200-300 9mm rounds per week), I'm setting the crimping/seating die at no crimp and seating at 1.120". I'm testing three or four rounds, one at a time, to ensure I am getting consistent results, and I am.

As I'm reloading, the COL of the rounds lengthen, getting into the 1.130" to 1.137" range, and a couple of times even longer. This length still passes the "plunk" test in my XD(m) barrel, but I am having to dial it back every 20 rounds or so to get close to the 1.120" again. I see no die movement when I am reloading; the dies are tight and the bushing is still locked in place.

Now I know from reading, since I am using mixed and untrimmed brass, and lead bullets (135 grain LRN from BlackAndBlueBullets.com) there will be some variance in COL. I'm only concerned because in my mind,if COL is going vary by 0.01+", shouldn't it also vary to the low side? Shouldn't I get readings of 1.130" and 1.110"? I never do, it's always on the high side. Eventually I dial the seating die back down, but having to stop, test, and readjust every 20 rounds or so really slows the progress down.

I never experienced this much variance in my single-stage press, but I also never used these bullets until I went to my progressive.

I am worrying for nothing?

Thanks for the feedback folks,
Tony.
 
Maybe the shell plate is tilting when you are setting it up because you don't have all the stations loaded, then tilting back when all the stations are loaded, changing the OALs.
 
This length still passes the "plunk" test in my XD(m) barrel
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I am worrying for nothing?
Click to expand...

Yeah I think so. Are you measuring from base to tip? This measurement is notoriously irregular as the bullet 'tips' vary.

Others might tell you different but the 'plunk' test does it for me.

P.S. There are (I've never bothered to buy one) gauges that measure from base to the ogive and these might show that your rounds are all fine but again I'd go with the plunk test.

Here's some extra info:

http://www.midwayusa.com/product/23...ad-bullet-comparator-basic-set-with-6-inserts

http://www.bergerbullets.com/effect...coal-and-cartridge-base-to-ogive-cbto-part-2/
 
this one drives me crazy too, being a little anal retentive! I noticed the same going between an old Rockchucker and the Dillon XL650. But, as others have said they all case gauge and fire fine. I added one of the Redding Competition Micrometer seating dies so at least I am confident that all the base to the ogive measurements are close as I do believe a lot of it is in bullet tip irregularities.

I did a test on several of the bullets I was using and just measured the bullet and noticed variations, now it could be the calipers are not Mitutoyo calipers and exact (using RCBS digital caliper) or there is variation from bullet to bullet (from tip to base).
 
I'm setting the crimping/seating die at no crimp and seating at 1.120".
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Is it safe to assume that you're loading 9mm?

....but I am having to dial it back every 20 rounds or so to get close to the 1.120" again.
Click to expand...

What exactly are you dialing back? The whole die? Just the seating stem? And how are you dialing it back?

I see no die movement when I am reloading; the dies are tight and the bushing is still locked in place.
Click to expand...

What die are you using? Are you sure the seating stem isn't working it's way loose and screwing itself upward a little bit each time you seat a bullet? I had this happen with the decapping stem on one of my dies. Carelessness on my part as I didn't tighten down the lock nut tight enough.
 
Higgite...

Yes, I'm reloading 9mm, mixed brass with 135 Grain Coated LRN bullets. My dies are Hornady's custom grade carbide.

When I dial it down, I'm turning the seating stem only. The bushing is still tight in place and the die is locked town tight against it.
 
PA-Joe...

All five stations were filled and running.

1. Resizing Die
2. Expander
3. Powder Drop
4. Seating Die
5. Crimp Die
 
I don't know if you have already checked this, but-
The seating stem on my Hornady seating die will veeeery slowly back out if I don't lock it down tight. Are you locking the seating stem on the die down? In my experience, you have to tighten the ring around the stem down hard enough to deform that rubber gasket a little.
 
Put a registration marks on the die threads and nut and the press with a pencil. Watch to see if any one of them shifts.

Measure a dozen rounds made early on, another dozen made about half way through the batch, and another dozen made at the end of the batch. Do this for a few sessions. See if the average or the length standard deviation are changing, and if they are changing the same way every time. If so, it will make sense to adjust the seater down at the round count where it begins to happen.

I don't know what the bullet coating you have is, but if there is standard wax lube present, it can build up in the seater stem and be warmed up and softened as more loads go through, making it easier to squash out of the way. Take the seater stem out and look for signs of build-up or other congestion.
 
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