Inconsistant seating depth when loading 9mm?

[Jim K III]

I'm fairly new to reloading handgun ammo and am trying to work out the kinks. One of them is that I get inconsistant seating depths when seating the bullets. Here are the particulars:

bullet: 115gr RN x-treme (plated)
powder: W-231 @ 3.8gr
dies: Hornady Custom Grade Titanium Nitride

I set the seating die to seat the bullets at 1.155 (OAL is 1.169). After seating 5 bullets I check each one with a caliper. Most seat depths are ~1.155 + or - a thousand or two. However, every once and a while one will seat @ ~1.165. See pics. I check for grit in the shell holder, make sure the seating adjuster isn't walking, insure the primer is fully seated so its not messing with the caliper, - but all is good and there is no slop in the press. And the caliper is good too - no slop in it. Out of 100 rounds loaded today 80 were between 1.153 and 1.158 and 20 anywhere from 1.150 to 1.165.

I can see when shooting that every once in a while there is a flier far out of the pattern, but should there be a 'flier' when seating bullets? Is this normal SOP? Am I being anal about trying to make sure they all seat as close to 1.155 as possible? Shouldn't a press, when set up secure and tight, seat everything at the same depth?

Most are around 1.155


but some are longer or shorter:

 

[kmw1954]

Most likely it's the bullet.

I had a box of those that I was having a horrible time with. Finally pulled that box and set it aside as I had another full box. As soon as I switched boxes of bullets the problem went away.

 

[Walkalong]

1.169 is the SAMMI max for 9MM, I've never loaded any that long. I generally load 115 Gr RN 1.130 to 1.135 OAL, yep, a .005 spread. A better fitting seater stem with keep the spread smaller, but a .005 spread is pretty common in 9MM with RN bullets.

 

[Pottimus]

Just curious, do the long ones seat any deeper on a second pull/try...what if you spin it 90 degrees? I am thinking inconsistencies in ogive contact in the bullet seat cone...these are cast and plated I believe, you seem to have eliminated any die/shell holder interference...I really don't feel like that would cause to much of a accuracy problem, with a bullet not known for accuracy...My 9mm pistol has feed problems with seat depth issues...

 

[Jim K III]

Just curious, do the long ones seat any deeper on a second pull/try...what if you spin it 90 degrees? I am thinking inconsistencies in ogive contact in the bullet seat cone...these are cast and plated I believe, you seem to have eliminated any die/shell holder interference...I really don't feel like that would cause to much of a accuracy problem, with a bullet not known for accuracy...My 9mm pistol has feed problems with seat depth issues...

A second pull/try does not seat it any deeper, nor does spinning it 90 degrees. It's quite strange. Right after one that seats long, the next several will be right back at ~1.155. I'll crank mine down to ~1.130 as Walkalong suggests.

 

[243winxb]

Hornady video on 9mm seat die adjustment.

I have seen online where the sliding sleeves gives problems? Have you cleaned the new dies.

I use RCBS, so not much help.

 

[Jim K III]

Hornady video on 9mm seat die adjustment.

I have seen online where the sliding sleeves gives problems? Have you cleaned the new dies.

I use RCBS, so not much help.

Excellent video - thanks for posting it.

 

[AgPilot]

Mixed brass seems to seat different if I leave the press and dies set the same.

 

[nettlle]

Mixed brass shouldn't make a difference.

 

[higgite]

If you are using a combo seating/crimp die, that can affect seating depth as longer cases start crimping sooner in the seating stroke than shorter cases and can actually keep the bullet from seating as deeply as it would in a shorter case. In my experience with mixed brass, it is hard to get consistent COLs with a combo seating/crimp die due to the inconsistent case lengths.

Another possibility is the bullets are just inconsistent in OAL. The difference is usually at or near the bullet tip. If you are using a seating stem that bears on the bullet ogive, you may well be getting consistent seating depths but inconsistent COLs.

If you're using a blunt seating stem intended for flat point bullets, it can flatten the point of a RN bullet during the seating stroke, usually very inconsistently, giving you inconsistent COLs.

 

[CoalCrackerAl]

Maybe your short stroking the ram?

 

[nettlle]

Seating stems can make a difference. The seating stem in Dillon dies can be flipped and if I don't do so with some bullets I will get seating inconsistencies. I am not familiar with Hornady dies. Other than that it would be play in the dies or die head. Or play in the ram. If the bullets are the same shape and size the seating problem isn't the bullet.

 

[Skeptic13]

The swaging process use to create lead bullets is not consistent. So bullets tend to vary in length. The cheaper the bullet the more variation you will see. However if you measure the cartridge length with a comparitor you will get more consistent results. Comparitors measure the length from the bottom of the case to the shoulder of the bullet. The shoulder is what your seating die contacts when seating the bullet. To me this is a lot of waisted time for 9mm. If it plunks it will shoot. That's good enough for me.

 

[gifbohane]

1.169 is the SAMMI max for 9MM, I've never loaded any that long. I generally load 115 Gr RN 1.130 to 1.135 OAL, yep, a .005 spread. A better fitting seater stem with keep the spread smaller, but a .005 spread is pretty common in 9MM with RN bullets.

Like walkalong said. 1.169 is the MAX. I also think that 3.8 grains is lite. Most guys use somewhere near 4.5 grains of W 321. BUT you have to work up your own loads.

 

[Klaatu Barada Nikto]

Was it new brass or range brass?
I'd go back and check the primer seat depths. I had a similar problem then I began a practice of depriming, primer pocket brush and then wet tumble with SS pins, no more variances in length for me, all were withing +/-.002.

 

[nettlle]

The brass has nothing to do with it.

 

[Klaatu Barada Nikto]

Certainly does if the primer pocket has crud in it.

 

[blue32]

Another possibility is the bullets are just inconsistent in OAL. The difference is usually at or near the bullet tip. If you are using a seating stem that bears on the bullet ogive, you may well be getting consistent seating depths but inconsistent COLs.

Jim, do you have this problem with flat points or only round nose?

 

[nettlle]

I have reloaded 35K + 9mm and 45acp. I tumble them but have never cleaned a primer pocket (for straight walled pistol). I don't have seating problems.

 

[Klaatu Barada Nikto]

I'm fairly new to reloading handgun ammo and am trying to work out the kinks. One of them is that I get inconsistent seating depths when seating the bullets...]

Are you on a progressive press?
When doing mockups I've found seating and crimping using a progressive press and leaving stations 1 thru 3 open, only setting depth on station 4. The shell plate can experience vertical runout.
Once all the stations are loaded and running my COL does change slightly. Make an adjustment and then let the train run.

 

[milsurpguy]

I had cbc 9mm brasa that was super hard, seating depths were all over the place with Sierra hollow points. FMJs probably would have been fine.

 

[tightgroup tiger]

I had cbc 9mm brasa that was super hard, seating depths were all over the place with Sierra hollow points. FMJs probably would have been fine.

I've had the same experience with mixed brass.
A lot of things can affect OAL and hard stiff brass is one of them.

 

[243winxb]

Mixed brass seems to seat different if I leave the press and dies set the same.

Different dies= Different results. In 45acp range brass, the neck tension can be very different, but has no effect on finished col.

9mm Luger
I found range brass trim length is loadable with .012" difference between shortest to longest. When New RCBS dies are adjusted correctly.

One brass was longer then .754" SAAMI maximum by .002" , but chambered & fired ok. Then it got trimmed.

No sorting range brass for me, but each gets checked closely. No maximum loadings. 700X- 3.2 grs- Lee 356-120-TC cast bullet. Sized to .3568" Wspm primer. OAL 1.045"

 

[Blue68f100]

I agree with the others, mixed brass and cheap bullets can cause OAL variations. Have you tried measuring your OAL using a seating stem so it does not contact the nose. This will give you a more consistent reading.

 

[tightgroup tiger]

I had the pleasure of getting a batch of real once fired brass from a friend and it was so soft and easy to work with. I actually could keep a good .002-.003" OAL through several hundred of them. First time I was ever able to do that on any of my presses.
With old hard crappy mixed 9mm brass, the OAL variance goes up to about .005-.006, on a good day, and could be more depending on the bullets I'm using.
I did this same experiment on my ABLP with new .357 mag brass and saw the same thing but not as pronounced as with the 9mms.
.002-.003 compared to .005-.006" OAL, most people won't care, but I've found the condition of the brass does make a small difference.