S1050 - Seating OAL for 9mm?

[LowBoost]

I finally setup my S1050. Everything seems OK with one exception. I am having inconsistent OAL readings. During my initial test rounds, I was using random range brass (mixed head stamps). After reading a couple of threads, I decided to sort my brass by head stamps and give that a try. I tried a few things and was still getting inconsistent OALs, so I decided to order the Redding Competition Pro Micrometer seating die.

After setting up the Redding die, I am getting a more consistent reading, but I have noticed a two scenarios:

1) When I adjust OAL for a single round, I can get a perfect reading (Say 1.1350) most of the time. However, when I start loading rounds (and the shell-plate is full) my OAL have a variation. It will be either shorter or longer (Sorry I don't recall which one exactly).

2) If I try to adjust the seating die with shell-plate full, it seems to take a long time (and rounds) before I can get one accurate OAL. And if I remove a case or two (To by-pass primer station) the reading will be off again.

I believe my process / approach could be incorrect? What am I doing wrong? Is my shell plate too loose? (Press is brand new). The closest I can get with a shell plate full is a .002 variation (Either short or long).

I will appreciate any input/suggestions on this.

 

 

[gregdavidl]

I've always found that when I set up the press with one round and then get a full shell-plate that the OAL will be slightly long.  By experience I know to give a slight extra turn when adjusting the dies with one round (make slightly short) and then check again after getting a full plate started.  I think it's just due to tolerance stack in the press and I have never thought it was a big deal.  Case lube helps to get better OAL consistency.  Once adjusted I don't do a lot of checking after that.

[LowBoost]

Thanks. I will give it a try now and see what I get.

 

[dillon]

When adjusting the seat die and crimp die, be sure to have a fired case in the size die. This ensures the same upward pressure on the toolhead that you will have when actually loading. Be sure to snug the die lock rings with cases/cartridges in the dies and the handle down.  However, .002" is insignificant. Most 9mm bullets vary much more than this. The most variation I've personally measured was a .026" extreme spread among 100 of a popular 9mm 115 grain FMJ projectile. Usually this variation is under .010"

[LowBoost]

*UPDATE* - I set the seating die with one bullet in the shell plate to 1.060 (For a CZ SP-01). I then backed out the die 7 thousands and loaded about 20 rounds non-stop.

I am seeing variations from 1.057 - 1.065. About 25% of the bullets are in the desired OAL. I would have expected 75%+ to be in my desired range. Is this normal/acceptable or is there something going on? That 1.057 is a "one-flyer", so I am disqualifying it from the test. 

Sorry if these are obvious questions. I am a newbie, but this is still pretty much the only "obstacle" I still need to overcome.

 

*EDIT*

I forgot to add, I am using Bayou Bullets 124gr TCG bullets. There is a lot of partying line issues with these bullets. So maybe this can be accountable for this? I will try some FMJs to see if this gets away some.

 

Edited November 23, 2016 by LowBoost

[jester121]

So you're seeing +/- 0.004" variation? Congrats!

That's not a problem, see the Official Dillon Word in the post above yours.

[LowBoost]

@Jester121 - Yes. I did some more rounds (100 total) and see a .002 - .004 variation. Many are spot on.

Thanks for the information. 

[noylj]

All these questions can be solved by simply measuring the COL of factory rounds and measuring the OAL of the bullet before seating. You can't get move consistent than the OAL of the bullets being used and factory ammo COL variations are not considered a problem.

Can someone tell me how, where COL is determined ONLY by where the bullet hits the seating stem and where the case head/shell plate is at, and the case length has NO effect on these two things, how sorting cases does anything or how a micrometer can help? Once the seating stem is set, it doesn't know there is a micrometer attached and the case is NOT even touched during seating (unless you are crimping at the same time). At least, I have NOT seen any change in COL from case length, where often the overall COL variation is greater than the sized case length variation (and the COL has not relation to the case length used). Measure and plot them.

All the variation I see is due to variations in the bullet (measure each bullet length and you'll see almost the same variation you see in the COL, and most of that is meplat variation—so get a seating stem that does not contact the meplat and measure COL from the ogive) and whether the shell plate is full or near-empty.

In reality it just doesn't matter. You aren't shooting precision rifle at 300 yards or longer. In fact, you probably aren't even shooting at 25 yards.

A COL variation of +/- 0.050" is a problem. A COL variation of +/- 0.006" is NOT a problem.

[MemphisMechanic]

Dont worry about an OAL variation of less than ten thousandths, as long as your gun shoots it accurately. Which it should.

Personally I load dummies and find what my gun will pass the plunk test with, given that bullet's profile.

Once I have that information I'll set my press up so that my longest round is .005" shorter than that length. So I'll load to 1.135 for a gun that will take a bullet out to 1.140 (which means at 1.140 it'll fall into the chamber, spin freely, and fall back out.)

The variation I'll see is typically 1.128" to 1.135" in that situation. Sometimes they'll dip down to 1.125" and that doesn't concern me either.

I'll go chrono it, shoot it for groups to make sure it'll shoot minute-of-upper-A-zone at 15 yards, and call it good.

(If it isn't accurate enough, I'll change powder charge and/or try a shorter OAL to find something the gun shoots tight groups with.)

Edited November 24, 2016 by MemphisMechanic

[Phlier]

22 hours ago, LowBoost said:

*UPDATE* - I set the seating die with one bullet in the shell plate to 1.060 (For a CZ SP-01). I then backed out the die 7 thousands and loaded about 20 rounds non-stop.

I am seeing variations from 1.057 - 1.065. About 25% of the bullets are in the desired OAL. I would have expected 75%+ to be in my desired range. Is this normal/acceptable or is there something going on? That 1.057 is a "one-flyer", so I am disqualifying it from the test. 

Sorry if these are obvious questions. I am a newbie, but this is still pretty much the only "obstacle" I still need to overcome.

 

*EDIT*

I forgot to add, I am using Bayou Bullets 124gr TCG bullets. There is a lot of partying line issues with these bullets. So maybe this can be accountable for this? I will try some FMJs to see if this gets away some.

 

Be careful loading to that short of an OAL.

So far, my son's CZ SP-01 hasn't had any problems out to 1.130 OAL with various bullets.

With some bullets, my 1050 will keep OAL variance down to .002. Others .08. I did have one batch of plated that had large ogive variations cause .15 OAL variations.

Edited November 24, 2016 by Phlier

[amada8]

My CZ P01 allows a max OAL 1.072" for some bullet profiles.  (Berry's FP for one)  Working a ladder up using that length hasn't been a problem for me.  Why the caution Phlier other than the obvious "you need to work a ladder up with that OAL to avoid extreme pressure"?  Don't we need to do that...... no matter what the chamber length for every new load?

Edited November 24, 2016 by amada8

[Phlier]

On 11/24/2016 at 0:41 PM, amada8 said:

My CZ P01 allows a max OAL 1.072" for some bullet profiles.  (Berry's FP for one)  Working a ladder up using that length hasn't been a problem for me.  Why the caution Phlier other than the obvious "you need to work a ladder up with that OAL to avoid extreme pressure"?  Don't we need to do that...... no matter what the chamber length for every new load?

Yup, we sure do. So how about, "Be careful working up a load when loading to that short of an OAL, as even very small changes in powder charge will have a much more pronounced change in pressures than at longer OAL's."

Edited November 26, 2016 by Phlier

[IHAVEGAS]

I'm assuming you are using the swage on your 1050, that is going to give you varied force on the shell plate depending on what condition the swaged primer pocket is in, also you may have better luck with the spring removed in your Redding seating die (I emailed and asked them about a weaker spring & they said some folks just take it out, no worries). Another thing to wonder about is whether or not a Lee U die or similar would effect consistency. 

I do not think you have a problem, but it is fun to get things as good as we can. 

[amada8]

:thumbs up: to Phlier

[LowBoost]

Yes - I am indeed using the swager on my 1050. The SP-01 I refer to also has a max OAL 1.080. The manuals, loading info, and recommendations I read for CZ they all range from 1.060 - 1.080 with 3.2 - 3.8 grains. That's what I loaded. I am fully aware of the pressure effects a shorter OAL. I will obviously chrono them this weekend.After all of your comments/suggestions, I am no longer worried about the "minimal" variation I am getting. (Mostly .002 - .004 and a one off at .005). 

I will now read on how to improve powder consistency. I will start by polishing the bar to see if it helps. Not that I am having a huge deviation, but I just want to make sure I can get the most consistency as possible. Since I got interested in reloading I have tremendously increased my reading time. (Seriously, 6 - 7 hours a day!)

[Phlier]

Deleted. I've been reading up on the CZ forums, which pretty much answered my question.

Edited November 26, 2016 by Phlier