Inconsistent OAL

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KeNd0

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Picked myself up a Hornady Lock N Load AP at Cabellas in the US last week, as an early xmas present to myself :). Using my 40 S&W Lee Deluxe Carbide dies with Hornady 180gr XTP, I am getting some inconsistency in my OALs. I set up the press, tested each station individually, ran three powderless, primerless cases to seat bullets to get OAL to 1.130. Ran 50 off and found them all within 1.120 - 1.124. Weird.
Adjust bullet seating die again to three 1.130. Run off ten, and find a few over 1.140, a few at 1.135. Run each one back through until I get 1.129 - 1.132.
Thinking I really should not have bought my #10 shell holder from the bargain cave, I decide to mark the 5 stations, and 5 casings 1 thru 5. Run them through and get;

1ST Run
1) 1.135
2) 1.135
3) 1.136
4) 1.136
5) 1.137

Rerun each in its same slot, just through bullet seating die and get;

2ND Run
1) 1.129
2) 1.131
3) 1.129
4) 1.130
5) 1.130

Is this normal? I have dissassembled and cleaned the BSD to eliminate that problem as well. Any ideas, or am I over analyzing this?
Should it take two passes to get desired OAL?
 
I think it's fairly normal as the bullets probably are not perfectly sized the same. I could be wrong though.
 
I had problems with Hornady 150 grSP in .312" giving me o.a.l. differences of
0.010" - 0.015". Took a while to figure out that it was the bullets themselves.
Three very distinct lengths in the same box of bullets.
Worthwhile checking it.

If it is the same bullets in the same casings going through the same die and
giving you different lengths, is it possible handle speed might be the culprit?
Cranking out five in a row, fast as you can, might give you different results
than going slowly, checking for any binding, looking for something wrong.
Just a thought.
 
My thoughts

Compressed load will do this

Loose shell plate or slop in the carrier

Inconsistent bullets

Case mouth expander not set deep enough, bullet base forced to size brass

Some startup and finish runout is normal on a progressive because the resistance on the linkage changes when not all dies are occupied by a round.
 
The difference is about .002". A human hair is about .003" to .004". Trying not to be a smartass here, but you are splitting hairs. If you are measuring with a vernier you can squeeze .002" if you are ham handed. There is a good chance the difference is in the ogive of the bullet and the spring in your press. Nothing to worry about, factory ammo isn't that close.
 
maynard said:
The difference is about .002". A human hair is about .003" to .004". Trying not to be a smartass here, but you are splitting hairs. If you are measuring with a vernier you can squeeze .002" if you are ham handed. There is a good chance the difference is in the ogive of the bullet and the spring in your press. Nothing to worry about, factory ammo isn't that close.
Click to expand...

Reread his first post, he's setting up for 1.130 and getting anywhere from 1.130 to 1.140... Not huge but even my LM had less variance then that.
 
What was baffling me was, if on second pass I achieved my desired oal, what is preventing it from achieving it on first pass. When I figure this out I believe I will cure the inconsistency as well.
 
- Clean the seater plug.
- Seater plug tight in die.
- Make sure press handle is bottomed out, and consistent.
- Compressed loads, use longer drop tube.
- Enough bell on the case mouth.
- High primers, inconsistently high primers.
- Burrs, dings. ejector marks on case.
- A combination of several factors.

- Measuring instrument not accurate.
 
KeNd0 said:
What was baffling me was, if on second pass I achieved my desired oal, what is preventing it from achieving it on first pass. When I figure this out I believe I will cure the inconsistency as well.
Click to expand...

It's normally something simple, I have heard of the carousel on a LNL coming loose before and causeing a runout problem on another forum but I can't find the thread... Double check all the nuts and bolts for the carousel before you start pulling your hair out! Good luck!!
 
Last edited:
OK. Went over everything. Found a couple pieces of stray powder squished onto face of Crimping die. It may have been a little close to begin with so I cleaned it off and backed it out a touch. Tested seating with case in each other station (two stations occupied at a time), individually and all stations. There definitely is a slight difference. After watching everything very closely, I noticed a primer not seated all the way. Found my primer seater punch had become loose. Doh! Reset bullet seating die to desired OAL, and after completing another 50, found 6 with slightly longer OAL, one with shorter, which I assume is the last one through. Overall very happy with this press, and am slowly getting the hang of it. Thanks for your suggestions guys.
 
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