Inconsistant bullet seating depth when reloading 9mm

[Ruger 15151]

I am a relatively new reloader, currently loading 9mm and have become very frustrated with the inconsistency of my COL. Although I am targeting 1.145, I am seeing several finished cartridges ranging from 1.140 to 1.152

-124gr Xtreme RN bullets (.356)
- 5.4 gr of BE -86
- Lyman M-Series expander die with .002 flare
- Lee seating die
- Crimp in separate step with LEE FCD (COLs measured before crimping)
- mixed range brass that has been wet tumbled in SS media
- Hornady LNL classic

I know that the longer cases typically feel like they have more case tension during seating and the shorter cartridges have noticeably less resistance when seating. I have noticed a more prominent ring on the bullets caused by the seating stem on the tighter fits. I'm sure that the depth of this indention is the source of the varying COLs. Separating cases by head stamp would clearly help. However, I am loading 9mm for target (not Bullseye) and plinking so its not realistic to separate the brass the way I do when reloading riffle rounds.

Wet tumbling in SS media removes all powder residue from the inside of the cases. I have wondered if the lack of residue on the inside of the cases requires more pressure when seating the bullet.

Should I use a bit of case lube?

Given that I could chamber 1.169 rounds in my 9mm, I'm not in danger of hitting the riffling with the 1.152 rounds. However, I want to have consistent, repeatable reloads.

What is a reasonable variance before I will start seeing POA and accuracy changes?

Any advice would be greatly appreciated.

 

[dgod]

I go thru a little process, I start with a Sized, Deprimed case, I try to bell the case slightly, then I set the desired bullet into the case just slightly (Ensure it is in the case straight), then I make sure it will function in the magazine, then I place the bullet in the magazine, and let the slide fly, ensuring that the slide went completely into battery, I then carefully remove the bullet, determine the Overall Length. This length will be to the edge of the Lands/Grooves. Back Off that a small amount, I use .010 for Rifle, and .015 for Pistol. There is no reason, just an arbitrary amoumt I selected. At this point, I know what Cartridge Overal Length I want for consistency.

Having done this, I have noticed (After trickling powder onto a 5-0-5 scale), the consistency is Much better. I'm getting Standard Deviations of 12 fps, 14 fps, and at the top, (Or Bottom), 44 fps. These Deviations are usually over 10 rounds with the chrony.

This is just my $0.02. Use it if you like, or don't if you don't

 

[ArchAngelCD]

First you should measure the COAL after you crimp since that is the completed round. It's possible your brass is at different stages if work hardening so the spring back is different. That could cause your different measurements. You might be pulling the handle at different pressures too.

If you have new or verifiable once fired brass from the same box of ammo, use that brass to load up some ammo and see if the OAL is closer to what you are aiming for and more consistent.

 

[Ole Joe Clark]

Are you stopping your seating operation the same way each time? I like to have a positive stop for my press handle to press against on each operation.

 

[LiveLife]

9mm ... targeting 1.145, I am seeing several finished cartridges ranging from 1.140 to 1.152

-124gr Xtreme RN bullets (.356)
- Lee seating die

I have noticed a more prominent ring on the bullets caused by the seating stem ... Separating cases by head stamp would clearly help ... I want to have consistent, repeatable reloads.

No. Since Lee seating die stem (Bullet Seater Plug) pushes on the bullet ogive further down from the tip, sorting brass by head stamp won't help but using bullet with more consistent nose profile will.

Range of 1.140" to 1.152" when you are targeting 1.145" with plated RN bullet is not too bad and I would consider average. If you want more precise OAL, you can use a custom stem so it matches the nose tip of the bullet you are using and Lee Precision offers this service for $8 + shipping with 4 week lead time - http://leeprecision.com/custom-bullet-seating-plug.html

What is a reasonable variance before I will start seeing POA and accuracy changes?

That depends on several reloading variables, including OAL variance. But do some testing and see if your shot group size changes. Sort your finished rounds by OAL and range test 1.145" rounds with rounds that vary from 1.140"-1.152". If you can't tell the difference on group size, don't worry about it.

When I do load development for accuracy, I will set the OAL slightly longer than my target and incrementally seat them down to length I want for more consistent bullet seating depth. Yeah, I know ... OCD ... And once I determine the powder charge that produces the smallest shot groups repeatedly, I will load away accepting the OAL variance of finished rounds by a few thousandths.

I use mixed brass and Lee dies and on the "Mixed brass and plated bullet" thread, I actually did a comparison test of once-fired Federal brass (.FC.) and mixed brass (WIN, Blazer, RP, FC/.FC. etc.) that have been reloaded several times but I could not identify any significant change and the mixed brass group turned out to be smaller - https://www.thehighroad.org/index.p...lets-in-9mm-40s-w-45acp.799231/#post-10195002

For once fired vs mixed brass testing, RMR 124 gr JHP bullets were used due to more consistent nose profile and resulting OAL (Note - Rounds loaded for comparison test and not for smallest shot group size and full powder work up with RMR 124 gr JHP will be conducted in the future).

 

[firecaptain53]

When reloading 9mm, I also try to achieve 1.145 and find that most will be between 1.138 and 1.154. I use mixed brass and these can be once fired to USPSA pickups that have been fired multiple times. I have sorted the finished cartridges by OAL and shot them to try and find any noticeable difference in accuracy at short ranges but could not. I think the biggest difference comes from the shooter themselves more than the slight difference in length.

 

[Walkalong]

With a good fitting seater stem a .005 spread on OAL is reasonable to expect.

 

[rfwobbly]

This is a very common novice complaint. Some suggestions...
• Lube your brass
• Lube your press
• Make a conscious effort to swing the op lever the exact same SLOW & STEADY speed each time. This is NOT a race.
• Use one brand of brass
• Get a form-fitting seating anvil that fits the ogive of your bullet.

Obviously your best results are going to come from FP bullets using a flat seating anvil. Buy 100 FP bullets and practice. Or, Lee can send you a form fitting seating anvil for a very few dollars. The last Lee seating die I saw had such a generic anvil that it wasn't going to excel at any bullet shape.
.

 

[Walkalong]

Obviously your best results are going to come from FP bullets using a flat seating anvil.

Yep, and I use one whenever I can. But that said, if a .010 spread in OAL with a RN is less accurate compared to a .005 or less spread, it will be hard thing to prove on paper.

 

[rfwobbly]

But that said, if a .010 spread in OAL with a RN is less accurate compared to a .005 or less spread, it will be hard thing to prove on paper.

You are correct. Measured over a chrono, using mixed brass would probably result in a greater SD than using single brand of brass with a 0.010" wide OAL tolerance.

 

[Walkalong]

Long ago I broke down and bought some Starline .38 Spl brass to try to get the ES & SD down, but it didn't do any better than mixed brass, nor could I shoot better groups with it.

With the much smaller 9MM case I imagine using all the same brand/lot of cases would make a bigger difference, but I have shot both mixed and matched cases and again, I can't shoot the difference up close. I recently scrapped my batch of mixed 9MM brass and picked out all FC cases. The only thing is they are a wide range of FC cases and not the same lot. It will be interesting to see if I notice an improvement. I would assume it would help, but how much? Enough for an average shooter like me to tell?

Anyway, .010 spread on OAL isn't something to stress over, but less is nice and the posters have given some ways to get there.

 

[Ruger 15151]

Anyway, .010 spread on OAL isn't something to stress over, but less is nice and the posters have given some ways to get there.

I think my process is sound because I only get .002 variance in COL when loading .223 and .308 with harder FMJ bullets.

However, my 9mm seating stem makes pronounced ring, especially when seating plated bullets in tighter cases. I think the depth of the indentation, length of the bullet, and case tension variations with the mixed brass all contribute to inconsistent COL.

I was just curious what variance you guys are seeing with 9mm plated bullets and what seems to be the acceptable range. Once I decide on the 1 or 2 bullets that I am going to stick with, I think I will take your suggestion and have Lee make a custom seating stem for them.

Great suggestions everyone. Thank you for sharing!

 

[Ruger 15151]

Obviously your best results are going to come from FP bullets using a flat seating anvil. Buy 100 FP bullets and practice.

I prefer loading FP and HP bullets and you are spot on... they load straighter with less variation in COL. However, my Storm Lake barrel has a vary shallow chamber so I have to load them at 1.050 vs 1.145 with my RN loads.

Therfore, I actually started another thread asking if anyone with a similar short chamber had found a more rounded HP or FP with less of a pronounced shoulder that could loaded a bit longer.

 

[CZ9shooter]

I struggled with this once too. Sorting your brass will make a a big difference. That's the easy part. Next step would be using a custom seating stem.

 

[Walkalong]

However, my 9mm seating stem makes pronounced ring,

Chuck the seater stem in a drill and slightly round off and polish the sharp edge. This will make the mark go away, get more contact, and may help the consistency of depth.

 

[murf]

pull the stem out of your seating die and make sure your bullets will go all the way through the die without dragging, or sticking.

murf

 

[Walkalong]

Good point.

 

[Drail]

Ruger 15151, Storm Lake ships their barrels with what is known as a "short reamed" chamber. They assume that the smith will use a finish reamer to cut it to the depth desired for a customer's chosen loads. Most match barrel makers do this.

 

[murf]

not all bullets are what the package says they are. you might want to put the calipers to a few bullets and verify they are .356"
in daimeter.

murf

 

[LiveLife]

OAL of finished rounds is determined by how the seating die stem pushes on the bullet nose, possible bullet tilt during seating and amount of tilt/deflection of shell plate if loading on a progressive press.

Since OP is using a single stage Hornady LNL Classic press with Lyman M-Series expander die and X-Treme bullets, I am focusing on the seating stem to further reduce the OAL variance. If the OAL variance is from bullet nose ogive, solution is custom made seating stem or a different bullet with more consistent bullet nose.

Personally, I would shoot the reloads first and see if target group changes from 1.145" rounds to other rounds with OAL variance before I change anything. If target group size does not significantly change, I wouldn't fix anything.

 

[Ruger 15151]

Chuck the seater stem in a drill and slightly round off and polish the sharp edge. This will make the mark go away, get more contact, and may help the consistency of depth.

That suggestion worked very well. Thank you. You guys are a wealth of knowledge.

Also, I noticed that a slightly larger flare to allow the bullet to sit another 1/32 lower in the case before seating brought the variance down to between 1.143 and 1.147. In addition, the resistance while seating was much more consistant and the stem left little or no witness marks on the seated bullet.

 

[Ruger 15151]

Personally, I would shoot the reloads first and see if target group changes from 1.145" rounds to other rounds with OAL variance before I change anything. If target group size does not significantly change, I wouldn't fix anything.

I will do that this weekend. Thanks for the suggestion.

 

[Ruger 15151]

Ruger 15151, Storm Lake ships their barrels with what is known as a "short reamed" chamber. They assume that the smith will use a finish reamer to cut it to the depth desired for a customer's chosen loads. Most match barrel makers do this.

Drail... Wasn't aware of that. In fact, when I called Storm Lake and asked if they had "short" chambers he said No. However, BDS reminded me that everyone's chambers are machined to SAMMI specs so the case seats correctly. I verified this with an empty sized case. It seated to the same (within a few thousands) in my my barrels including the Storm Lake.

Therefore, the Storm Lake barrel must have a "short reamed" chamber because that same case with an HP seated at 1.100 hits the lands. Its makes sense that these target barrels have a "shorter ream" so they can be customized to the correct bullet jump of a shooters favorite load.

Great information. Thank you!

 

[9mmepiphany]

Also, I noticed that a slightly larger flare to allow the bullet to sit another 1/32 lower in the case before seating brought the variance down to between 1.143 and 1.147. In addition, the resistance while seating was much more consistant and the stem left little or no witness marks on the seated bullet.

A complimentary step would be the bevel the inside of your case mouths. Just a light touch makes bullet seating much smoother

 

[Walkalong]

Therefore, the Storm Lake barrel must have a "short reamed" chamber because that same case with an HP seated at 1.100 hits the lands.

The "chamber" is where the brass fits. The brass and brass only. If they are leaving something short, it is the transition from the chamber to the rifling.