What did I screw up?

[rp-]

Ok. Lee breech lock challenger press. Lee three die 9mm set.

I have previously used this set for about 1700 rounds. Recently got another 1000 hap bullets and started loading today. I pulled one of the bushings off the seating die to use for a different die but have since gotten a new bushing for it. I have previously sized, expanded, and primed all of my brass.

Tonight I load up a round to adjust my overall length. I get it adjusted down to where I want it. Load up another round, it is +.006. Ok, maybe just difference in ogive. Load another, it come out -.0075. Well that's odd... Load up a few more and check, I'm landing between 1.1175 up to 1.1350. What the heck?!?

Clean my die, test with 5 more rounds. 1.1150 to 1.1305

Clean my press, 5 more rounds, same results

Remove the RAM, clean, clean some more, reassembled. Getting 2-4 rounds between 1.1230-1.1265. The. I get one at 1.1330.

No adjustment. Run 2-3 more rounds in the 1.123 - 1.126 range. Then I get one at 1.119. Next one at 1.135.


What the hell did I miss here?!?!?!?

I'm going to sleep.

 

[Mreed911]

Compressing your powder? Powder change?

 

[jrbfishn]

Check the bullets carefully. Shape and overall length.

from an idgit coffeeholic

 

[jrbfishn]

Check to make sure your die is locking in place correctly.


from an idgit coffeeholic

 

[Dawico]

It may just be the bullets themselves that vary that much.

You are measuring to too many decimal points. Just look at the first two decimal places and round them.

Try measuring the bullets themselves and see how much variance you get.

 

[Charlie]

It may just be the bullets themselves that vary that much.

You are measuring to too many decimal points. Just look at the first two decimal places and round them.

Try measuring the bullets themselves and see how much variance you get.

This ^^^^^ Especially the bullet measuring suggestion!

 

[robertc1024]

I always have a little variance, but that seems like a lot to me. I've found that OAL always seems to grow a bit with brass that is tighter on the bullet though. Some case walls are just thicker and have more friction when assembling the round than others.

 

[rp-]

Compressing your powder? Powder change?

I thought this could have been it. Went out this morning and started measuring. I grabbed about 10 rounds. 8 of them were between 1.1245 and 1.1260. I think my caliper may have just been effed up somehow. Didn't have a lot of time to look at it this morning though. Gonna try a new battery later and see how it goes.

I did have one round in the bunch that measured 1.1190 and one that was at 1.131. I took the one that was long and pulled the bullet to measure the powder. It weighed at 4.6. My load should be between 4.2-4.4 for what I'm loading.


What I figured out this morning: caliper may have been reading incorrectly. Powder measure not set right. I think I forgot to sail in my powder because I was too busy effing with OAL... Going to pull them all and redo tham all tonight.



As for the length of the bullets: I'm using hornady HAP. These are VERY consistent. In fact, I was upset that the XTP couldn't be this consistent. I don't recall now as it has been 6 months or so but as I recall the variation in the bullets was +/- 0.0020. I'll get so e better measurements when I get home though.


For now I'm off to pool guy it up for the day

 

[jrbfishn]

Tried to use my calipers last week after a few months. Wouldn't tead right either. That would definitely do it.

from an idgit coffeeholic

 

[robocop10mm]

You have calipers that read to 10,000th of an inch? 1.12 and 1.12 Same-Same

 

[Fragman]

Not so much 1/10000th of an inch, but many calipers go to half a thousandth. .0005


Sent from my iPhone using Tapatalk

 

[rp-]

Mine will read X.XXXxx. the last number is always 5 or 0 so I guess it's 5/10,000 or ½/100,000

 

[Governors20]

You aren't shooting benchrest with a handgun. I bet your groups wont notice the difference in the OAL.

 

[rp-]

No but when. My COAL goes from ±.0025 and suddenly jumps to ±.015 or more.... This alarms me. My goal COAL is 1.125.

Again, the HAP bullets come out pretty consistent. I'd say out of the 2000 I have loaded (some on another press used up at parabellum research) there was at least 95% within 1.1230-1.1260.

The bullets are pretty impressive

 

[Younggun]

Check case length if you seat/crimp in the same die.

If you have some longer cases they can crimp before the bullet is fully seated causing a longer AOL.




Sent from my HAL 9000

 

[rp-]

I'm pretty sure it was my caliper but I'll check that too when i get back at it

 

[Fragman]

Mine will read X.XXXxx. the last number is always 5 or 0 so I guess it's 5/10,000 or ½/100,000

Actually, 5/10,000 is the same as 1/2,000, or half a 1,000th, not half a 100,000th


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[rp-]

... I effed that up....

Should have been 5/100,000. It will read down to 0.00005.

So it should be 1/20,000 or ½/10,000, correct?

It was early and I wasnt mathing right. That usually doesn't happen to me. I'm usually pretty spot on

 

[robertc1024]

Nerd hat on. Uncertainty due to resolution is the resolution / square root of two because of a rectangular uncertainty distribution. Not that it matters, but this is the stuff I do at work all day.

 

[rp-]

Wait. What?