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View Full Version : 9mm Brass Resizing the Boolit from Seating



Shiloh
05-09-2011, 05:38 PM
Well folks,

How does one prevent this from happening? I removed a seated 9mm boolit and it has been sized down from .357 to .356. I can see my boolits hitting sideways,
patterning instead of grouping, and leading.

I am using 50/50 WW/Range lead. Do I need a harder boolit?? Do I need to try sizing my brass on a .38/.357 sizing die??

This is the LEE 125 gr Round Nose. Any suggestions are appreciated.

Thanks, Shiloh

bumpo628
05-09-2011, 05:49 PM
What size does your barrel slug?

GRUMPA
05-09-2011, 06:02 PM
I'd be more curious as to how hard his boolits are. Mine are 22-24BHN and I don't have that issue. And as far as using a 38\357 sizing die, if you were to do that your problem would be worse.

When I use the 357 sizer(backed up .060) it makes the brass actually smaller than my 9mm sizer die. Your problem would be worse than it is now I believe. It really sounds like your issues are compounded. 1 I really believe your boolits are to soft. 2 your getting an improper boolit fit to the bore.

Shiloh
05-09-2011, 07:13 PM
What size does your barrel slug?

Slugs at .3559 x .3562 Boolits drop from the mold at .3570 x .3576

Shiloh

Doby45
05-09-2011, 07:31 PM
I use a 357 powder through expander plug and then seat a .358 boolit in the brass and it is perfect for my 9mm. Mine slugged at .3565

Shiloh
05-09-2011, 08:47 PM
I use a 357 powder through expander plug and then seat a .358 boolit in the brass and it is perfect for my 9mm. Mine slugged at .3565

What do your boolits drop from the mold at?? What mold and alloy??

Thanks SHiloh

BeeMan
05-09-2011, 09:06 PM
Measure the ID of a case belled with your 9mm expander. Try an expander from a 38 or 357 die set and measure the same. See if you can get .001 more expansion all the way to the base of the seated bullet.

You will likely still need the 9mm expander to flare the case mouth.

Don't over crimp.

Harder may help but fit must be correct in any case.

Doby45
05-09-2011, 09:21 PM
My boolits drop at .359-.360 from both my Lee 125gr RNFP and my Mihec 359-125. My alloy is straight clip on WW and a touch of tin.

RobS
05-09-2011, 09:39 PM
Three ways around this:

1. If you are going to use softer alloys then an expander such as a Lyman M-die will go far enough into the case (as far as the boolit or a touch further) to open it up so it doesn't swage down the boolit. An expander .001-.002 under the boolit diameter usually does the job for softer alloys.

2. Size to a larger diameter in anticipation of the case swage. Some people do just fine with a .358 boolit some .359.

3. Use a harder boolit to resist the stress the brass places on the base of the boolit.

Allowing air cooled boolits the chance to age harden for a week or two helps as well. It doesn't matter what direction you believe the boolit needs to come from the case at the intended diameter.

RobS
05-09-2011, 09:43 PM
Also.........what dies are you using?

lead Foot
05-10-2011, 03:37 AM
Shiloh. You had me rushing to measure mine. Lucky I don't have your problem. My lead is 90% lino 8% pure 2% tin. I think your lead should be hard enough ~ mite be your dies. I use LEE dies and had trouble with the seating die. I size to .358 and just would not seat the boolit right. I ended up using a .38 body with the 9mm seater plug. Worked a treat.
Lead foot.

Ausglock
05-10-2011, 04:28 AM
G'day.
You aren't using a Lee Carbide Factory Crimp Die are you?
They resize the cast pill and ruin Accuracy and cause severe leading due to the undersize Boolit.

I run Lee dies but with a Dillon Crimp die.

Shiloh
05-10-2011, 08:57 AM
Also.........what dies are you using?


Shiloh. You had me rushing to measure mine. Lucky I don't have your problem. My lead is 90% lino 8% pure 2% tin. I think your lead should be hard enough ~ mite be your dies. I use LEE dies and had trouble with the seating die. I size to .358 and just would not seat the boolit right. I ended up using a .38 body with the 9mm seater plug. Worked a treat.
Lead foot.


G'day.
You aren't using a Lee Carbide Factory Crimp Die are you?
They resize the cast pill and ruin Accuracy and cause severe leading due to the undersize Boolit.

I run Lee dies but with a Dillon Crimp die.

Dillon Dies all the way around Gentlemen.

By the way, I received my six cav. LEE 120 gr TC conventional lube groove mold from Midway yesterday. I'll clean it up and try it today.

Shiloh

HeavyMetal
05-10-2011, 09:13 AM
Measure your expander plug and adjust as needed.

As mentioned in an earlier post this plug should be .001 smaller than your cast boolit. So if you want to load a 357 boolit the plug must be .356.

Many die sets are designed for Jacketed bullets and as such will be .004 smaller than bullet size to compensate for "grip" on the jacket.

RobS
05-10-2011, 09:30 AM
Measure your expander plug and adjust as needed.

As mentioned in an earlier post this plug should be .001 smaller than your cast boolit. So if you want to load a 357 boolit the plug must be .356.
Many die sets are designed for Jacketed bullets and as such will be .004 smaller than bullet size to compensate for "grip" on the jacket.

Not necessarily a must on the expander plug. Yes, .001 under boolit diameter is a viable expander diameter that will usually provide adequate neck tension for a plain base boolit that isn't hard enough to withstand the stress the case puts on the base of the boolit. However a tougher boolit can change this.