Inconsistant seating depth when loading 9mm?

Never had all rounds that were uniformed. +/- .01-.02 is acceptable, don't sweet the small stuff. But if it bothers you just put it back in the press and push down the handle a little harder to squeeze that .01 down.

A progressive press (Dillon) may have up to .010" variation in col. If a die contacts the shell plate, it may acts as a stop. The deck height (.125") may not be the same at each station. Each round from that station may have a different oal.

Here now is a whole list of things that can add to length inconsistency. Each one can be reduced or eliminated if one takes the time.

With direct experience with this problem and that exact bullet again the problem was inconsistency with the shape of the bullet. Same bullet with just a change of lot number eliminated the whole problem and I was back to my variance of .003" which in 5 calibers and 12 guns has not made a hill-o-beans difference in how they perform.

Jim K III said:

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.
but some are longer or shorter:
View attachment 1000058

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Looking at the second picture where the OAL is longer it looks like the brass is slightly bulged where the crimp is and it might be just the angle of the picture or the light on the brass. Are you using a roll crimp or a taper crimp? If you are doing a roll crimp not a true roll crimp and you have inconsistent brass length it looks like the die is trying to crimp before the bullet is seated to the depth that you want. If that is the way you are crimping try backing the die up a little so it is not crimping so hard early in the seating process. Or you could try seating maybe 10 or so bullets without any crimp to see if your COL is consistent that way. You do not need much of a crimp just enough to take the flair off of the case mouth. A taper crimp die works well for 9mm. +/- a couple thousands is nothing to worry about on COL

I help hundreds of novice reloaders each year. The one recurring issue they ALL have is wild variations in their cartridge OAL. So what you are experiencing is "normal".

Here's the heart of it... You should be working on a smooth, consistent stroke of the op lever. Reloading is like tennis, golf or anything else. You will need to slow down and concentrate on your stroke. Don't think about the ammo, concentrate on being smooth. After the first ~1000 rounds, most novices have developed their swing, and these type issues gradually disappear. When you get your "muscle memory" developed, you'll be able to reload and do other things, but for now focus on being smooth and steady.

Two suggestions that will really help...

• Place the Dillon calendar so that it's behind you.
• Consider using a case lube.

All the best.

243winxb said:

A progressive press (Dillon) may have up to .010" variation in col. If a die contacts the shell plate, it may acts as a stop. The deck height (.125") may not be the same at each station. Each round from that station may have a different oal.

Click to expand...

Why would a seating die contact the shellplate...?
Even the sizing die on a "straightwall" case won't (shouldn't) touch the shellplate.
While the deck height may not be the same at each station, the seating station would always be the same, as the round is only seated at THAT station.

rfwobbly said:

Two suggestions that will really help...

• Place the Dillon calendar so that it's behind you.
• Consider using a case lube.

All the best.

Click to expand...

FANTASTIC............

Soonerpesek said:

Why would a seating die contact the shellplate...?
Even the sizing die on a "straightwall" case won't (shouldn't) touch the shellplate.
While the deck height may not be the same at each station, the seating station would always be the same, as the round is only seated at THAT station.

Click to expand...

243winxb said:

If a die contacts the shell plate , it may acts as a stop.

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Change to "Any Die".

From my new RCBS 2021 9mm die set instructions.
View attachment 1000168

Soonerpesek said:

Even the sizing die on a "straightwall" case won't (shouldn't) touch the shellplate.
While the deck height may not be the same at each station, the seating station would always be the same, as the round is only seated at THAT station.

Click to expand...

On a progressive press the resizing die needs to touch the shell plate under full load or you don't know if the case is in the die as far as it can be due to plate flex. If it is not touching the shell plate under full load you will have more inconsistencies since a harder case could come along and the take full advantage of the flex in the shell plate. The shell plate gives instead of pushing the case all the way in the resizing die. When it is pushed down by the sizing die part of the shell plate it is teetering up somewhere else affecting something else, like the seating die.
If the resizing die touches the shell plate under full load every time then the other stations won't be affected by the flexing because the resizing die and case is loading the shell plate more consistently. The reaction on the other stations will be more consistent. The flex in the shell plate won't break a die. The flex in a shell holder on a single stage can.

From the OPs original post, it sounds like he is possibly using a single stage press for his 9mms.

Soonerpesek said:

While the deck height may not be the same at each station, the seating station would always be the same, as the round is only seated at THAT station.

Click to expand...

Not so for presses that rotate a different “deck” into position under the seating die with each pull of the handle.

I get slightly different OAL values on a Dillon if I seat a bullet with or without other cases in each station.

tightgroup tiger said:

The shell plate gives instead of pushing the case all the way in the resizing die.

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On the machine I use, the shellplate does "give" ever so slightly, however, the case bottoms out on the shellplate "holder", which would be an almost constant between the case and die at the top of the ram stroke.
I am sure to be corrected if wrong, but this is my thinking.
Also, on the machine I use, when sizing ( let's use .223 as an example) the sizing die does not completely contact the shellplate.
If it does, then I get too much "bumping" of the shoulder.
Again, this is all MY personal experiences.

243winxb said:

From my new RCBS 2021 9mm die set instructions.

Click to expand...

How many times does it state " DO NOT CAM OVER" in your new RCBS 2021 9mm die instuctions....?

Jim K III said:

One of them is that I get inconsistant seating depths when seating the bullets

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@Jim K III
Progressive or single stage press,
and, does your seating stem closely resemble the bullet profile...?

Soonerpesek said:

Also, on the machine I use, when sizing ( let's use .223 as an example) the sizing die does not completely contact the shellplate.
If it does, then I get too much "bumping" of the shoulder.

Click to expand...

I found this to be very true in the 1980s loading 223 on a Dillon RL-450. Each station was different.

The RCBS carbide dies & instructions seem to have changed over the years.

243winxb said:

The RCBS carbide dies & instructions seem to have changed over the years.

Click to expand...

Haven't we all..........!

I apologize for "derailing" the thread...
I have asked the OP a ? regarding HIS issue...

It's most likely the bullets. I just got a shipment of Berry's that have a different ogive reading than the lot I boughts 6 months ago, and there is variation between those.

Jim K III said:

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.

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I have experienced this myself loading 9mm. When I load 44 mag or special this does not happen! I use a lee 4 hole turret press (love it by the way) all my dies are also lee. I have wasted so much time measuring every damn 9mm because of this issue. I have come to a point that I "almost" dont care anymore with 9mm being off a little. If it don't visibly look off I'll let it pass. Havent had a problem, but I too get a flyer every now and then. I dont think there should be any issue other then the occasional flyer (if that even causes that) with 9mm, a little to deep or not deep enough isn't gonna blow up a 9, so at least it wont kill us... Frustrating for sure though. I hope there is a sure answer in here.
P.S Almost forgot, my problem was worse when I was using random brass. I have since started sorting and it did help a bit.

peeplwtchr said:

It's most likely the bullets. I just got a shipment of Berry's that have a different ogive reading than the lot I boughts 6 months ago, and there is variation between those.

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I use berrys and also have this issue with 9mm

I buy in bulk and keep the different lots seperated, so I can readjust the seating die once every 3 or 4k; low impact.

Plus they are mostly training ammo, so shot at 5 yards.

Jim K III said:

But the OAL should be the same if everything on the press is tight and the seating die ring is tightened. .

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That is correct as long as everything is stationary and the only thing moving is the ram and the bullet. It does come into play when there is a loose fit clearance such as a tool head or turret head that moved or not otherwise locked down. Which then the case can interact by imparting more or less restriction thereby moving the loose fitting part proportionally more or less on each pass.

This is why Lee and others put the ram under the first station as that is normally the position that has the sizing die and therefore takes the most force.

All of this is the reason I headstamp sort all my pistol brass. Because I want to achieve the same feel each time I pull the handle on my progressive or turret press. Then when something doesn't feel right or the same I stop to find out why. I find feel a very important sense when reloading. Rates right there with sight and sound.

https://xtremebullets.com/v/vspfiles/downloadables/RELOADING MANUAL.pdf

XTreme offers a free reloading e-manual. They call for 1.150 FYI, and this is probably what you should use until you learn more. They also recommend a “light taper crimp”. Carefully reread the instructions that came with your New Dimension dies on taper crimping and seating in the same step.

I’ve not used Xtreme and can’t comment directly to them.

Hornady calls for 1.100 for their 115 grain FMJRN (Win-231 and others) and Sierra calls for 1.100 with FMJRN as well. Speer calls for 1.130 for their 115 FMJRN (WSF and others). These would be similar bullets.

You don’t have a lot of bullet in the case which could be causing some of your problems - crooked bullet seating perhaps. I’m with Walkalong in seating around 1.130/1.135, and, as he says, 1.169 is a max OAL by SAAMI specs and should not be confused with a decent seating depth.

Some of the powder companies will use this dimension. For example, Hodgdon call for 1.169 for their WSF powder with a 115 FMJ (Hodgdon owns Winchester powder, btw), but then calls out for 1.100 with CFE pistol with the same FMJ. Having not used WSF, I can’t comment, but I might assume that WSF is a course powder and fills the case. We all know what assume will do for you.

Jim K III said:

Concerning mixed brass and different case lengths, should that really matter? I

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The amount of taper crimp will be different with untrimmed brass. But online, no one trims 9mm brass, so they say. If i find brass that is over SAAMI maximum, its getting trimmed.
Accuracy will not be as good using range brass of different manufactures.

From tne Lee website-

Another possible cause for bullet seating depth variation is seating and crimping at the same time when trying to apply a firm crimp to untrimmed cases. Variation in case length also causes variation in the amount of crimp applied. Long cases get a heavier crimp than short ones. When seating and crimping at the same time, the crimp is formed as the bullet is seated into the case. The crimp will form sooner on a long case, and therefore the bullet will not be seated as deeply. The solution is to seat and crimp in a separate step and/or trim cases to a uniform length.

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https://support.leeprecision.net/en/knowledgebase/article/seating-depth-variations