Thoughts on 9mm bullet setback

I would blame it on the plated bullets. I have been reloading 9mm a lot lately and I use a Lee sizing/depriming die, a Lyman M die for a flare, and a Lee or Lyman seating die. I have a Redding (dunno where that came from) and lightly crimp (not a real "crimp", just deflare). Earlier this week I reloaded some 9mm RMR 124 gr bullets in Blazer brass, no loose bullets. Last week I reloaded some Hornady and Speer 124 JHPs in mixed brass, no problems. Last month I reloaded a bunch of Speer Gold dots in mixed brass, same methods and zero problems. Also had a bunch of WCC mixed date military brass that also showed not problems with jacketed bullets. So, the only difference is the plated bullets (I have no use for plated bullets as from my tests in a few handguns, mebbe 1,000 plated bullets, they are of no advantage to me over my cast bullets or inexpensive jacketed bullets). I would suggest trying your methods, with your brass, with decent jacketed bullets and see if the bullets are the problem...

I would measure a couple bullets just to verify I didn't have an issue with undersized bullets.
I have 3 sets of 9mm dies, 2 Lee and one Hornady. Both my Lee sizers size tighter than the Hornady.
Might just be a stacking of tolerances, slightly small bullets, thinner brass, and a sort of loose sizer

Setback and neck tension is always a sizing or expanding problem; you can not fix it with crimping.

You've got a tolerance stack of bullet, brass, sizing die, and expanding die. Start measuring!

My guess is one of your dies is slightly oversize, and one of your headstamps is a bit thinner than average. You might also have undersized bullets. It's all guessing until you measure.

Im picky about neck tension too, and generally won’t use FC or Blazer because of it. There are others that act similarly, but those two I remember without notes at hand

I mainly load .357" and .358" diameter coated bullets in 9mm and never have a lack of bullet tension. However, when I load plated or jacketed in either .355" or .356" I've had the same problem as the OP, and why I now size with a U-die regardless of head-stamp.

Lee Undersizing dies

I had a similar problem with my SDB and the required dillon dies.

I replaced the sizing die and all was well. it was over 20 years old and had countless rounds through it.

Sometimes stuff just wears out.

I've noticed inconsistent neck tension with FC and Blazer brass. I have a lot of both and sort it when sizing, I can feel a difference in resistance when sizing it. The brass that is easy to resize goes in the scrap bucket.

Okcafe86 said:

Perhaps I'll get one of these Lee undersize dies, I do plan on avoiding that brass though.(FC/Blazer) Ive got tons of mil brass to make my way through.

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When I was loading 9mm I had same issue with FC brass and have 1000’s of them Got a Lee U die and have had no setback with either jacket or plated bullets.

As I mentioned earlier both my Lee dies size tiighter than the Hornady.
They are just the standard Lee sizers.
My Hornady die does not play well with some brass..
Sent it back to Hornady and they said it was in spec.
Same brass Lee die, no issues.
Drove me nuts when I first got my LNL progressive, had the Hornady dies in it
problems with no neck tension, messed with it a bunch thinking what the heck am I doing wrong on the setup
Swapped in my Lee sizer and the problem went away.
(I only messed with it for about an hour or two before it occurred to me to try the other die
)
Here is a link to the Lee U die
https://www.amazon.com/Lee-Precisio...ld=1&keywords=Lee+90313&qid=1590870264&sr=8-5
$20

Might be worth getting and then you probably won't have to worry about using the FC or Blazer brass.

Walkalong said:

Okcafe86 said:

9mm bullet setback ... plated 115gr rn ... noticed all of the FC and Blazer bullets pushed all the way into the case with minimal thumb effort.

Any thoughts on this lack of case neck tention?

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If your sizer is touching the plate when sizing a case and you have poor neck tension either the sizer is too large (ID) or the expander is too large (OD).

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Before anything, as Walkalong posted,

What does your resized brass measure (Inside Diameter of brass)?

And what does your brass measure after expander (Inside Diameter of brass)?

I would spend twenty dollars on a smaller die than sort, separate or scrap early nine millimeter cases.

I’ve had the same set back issue with RCBS dies, the problem being solved by a Hornady set. The sizing die diameter is important, regardless the brand. Just as the expander is too.

Set back in a 50A.E. is, unpleasant.

interesting posts...

viagrow said:

interesting posts...

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This is the beauty of the High Road I guess, there maybe more than one way to get where you need to get.

Good info above, but, since 9mm brass is abundant, you can pick and choose to any standard you choose. While I've not had the neck tension problem, sorting by headstamp and tossing the one(s) that give you trouble may be best for you. No big deal (I often have way more time for reloading than shooting so I spend time in my shop just doing "reloading stuff" like sorting, processing brass. Really bored last week so I cleaned and sorted about 200 9mm and 100 45 ACP brass. I was in the shop, doing reloading stuff and enjoyed that much better than TV. Keeps me in touch...

I really like my lee undersized dies and use them for all my 9mm brass. If it won't gauge or provide tension after a run through the lee U die its scrap.