.380/9mm

STW · February 8, 2013, 10:45 PM

Just curious.
The 9mm and .380 both use a .355 bullet, the cases are the same diameter, and the rims are the same size.
Why do they require different reloading dies?
Logic suggests that they'd be more like .38/.357 or .45/.454, needing only an adjustment to the seating die.
Where is my logic falling apart?

(Yes, I know they were birthed separately but the end result would seem to matter more then parentage)

ScottRiqui · February 8, 2013, 10:55 PM

The cases aren't the same size, and the rims aren't either.

The 9mm case tapers from .391" at the base to .381" at the mouth. The .380 case is .374" throughout.

The 9mm rim diameter is .394", and the .380 rim diameter is .374"

Although I've had a 9mm case sneak into a .380 loading session on my Lee press, and it does fit into the shell holder, Lee actually specifies different holders for the two calibers.

EDIT - Turns out I was mistaken, and you actually *can't* fit a 9mm Luger case in a .380 ACP shell holder.

highrolls · February 9, 2013, 03:28 AM

For what its worth, (Dillon Press) the case holder and position buttons for the 380 are the same set I use for .223 Rem. Not sure if that situation exists with other brand case holders. I knew that before I started reloading 380 so I saved some bucks by just using the .223 set with the 380 die mount.

Lemmon · February 9, 2013, 09:41 AM

I recently was reloading 9mm rounds on my progressive press. I always use a case gauge to check the round after it comes off the press to make sure it will fit my pistol. Better to check now than later. I found that 380 rounds will go through the progressive press easily and load. Glad I use the case gauge. It quickly let me know that I had loaded some 380's in batch which I immediately pulled the bullet to keep from making a dangerous mistake...

Lemmon from Rural South Carolina

higgite · February 9, 2013, 03:44 PM

When you say .380 and 9mm cases are the same diameter and same rim sizes, which 9mm cartridge are you talking about? Obviously not 9mm Luger.

dacaur · February 9, 2013, 11:13 PM

Quote:

Although I've had a 9mm case sneak into a .380 loading session on my Lee press, and it does fit into the shell holder, Lee actually specifies different holders for the two calibers.

Thats odd.... 9mm cases will NOT fit into my lee .380 shelholder (#4) and in a 9mm shelholder (#19) a .380 auto case is VERY sloppy (enough to easily slip out straight up if you angle the case a bit)....

ScottRiqui · February 9, 2013, 11:38 PM

Quote:

Thats odd.... 9mm cases will NOT fit into my lee .380 shelholder (#4) and in a 9mm shelholder (#19) a .380 auto case is VERY sloppy (enough to easily slip out straight up if you angle the case a bit)....

I checked again, and you're right. I also figured out what actually happened in my case:

I finished loading a round and when I put it in the styrofoam tray with the rest of the finished rounds, it stood a little taller than the rest. I looked at the markings and saw "9mm". I figured a Luger case had gotten mixed in, and just tossed it in my "rounds to be disassembled" bag.

But looking at it again, the case actually says "9mm Br. C", making it a .380 ACP round just like the rest. The reason it was sticking up in the tray was that there was excessive mold flash on the cast bullet, causing it to wedge in the styrofoam tray. The round was fine after all.

So long story short - you're right that a 9mm Luger case won't even fit in the Lee #4 shellholder for .380 ACP. I'll amend my earlier post.

February 8, 2013, 10:55 PM	#2
ScottRiqui Senior Member Join Date: January 27, 2010 Location: Norfolk, VA Posts: 2,905	The cases aren't the same size, and the rims aren't either. The 9mm case tapers from .391" at the base to .381" at the mouth. The .380 case is .374" throughout. The 9mm rim diameter is .394", and the .380 rim diameter is .374" Although I've had a 9mm case sneak into a .380 loading session on my Lee press, and it does fit into the shell holder, Lee actually specifies different holders for the two calibers. EDIT - Turns out I was mistaken, and you actually can't fit a 9mm Luger case in a .380 ACP shell holder. Last edited by ScottRiqui; February 9, 2013 at 11:39 PM.

February 8, 2013, 10:45 PM	#1
STW Senior Member Join Date: June 15, 2002 Location: Montana Posts: 147	.380/9mm Just curious. The 9mm and .380 both use a .355 bullet, the cases are the same diameter, and the rims are the same size. Why do they require different reloading dies? Logic suggests that they'd be more like .38/.357 or .45/.454, needing only an adjustment to the seating die. Where is my logic falling apart? (Yes, I know they were birthed separately but the end result would seem to matter more then parentage) __________________ "What kind of man would put a known criminal in charge of a major branch of government? Apart from, say, the average voter." - Terry Pratchett

February 9, 2013, 03:28 AM	#3
highrolls Senior Member Join Date: January 20, 2009 Location: already given Posts: 115	For what its worth, (Dillon Press) the case holder and position buttons for the 380 are the same set I use for .223 Rem. Not sure if that situation exists with other brand case holders. I knew that before I started reloading 380 so I saved some bucks by just using the .223 set with the 380 die mount.

February 9, 2013, 09:41 AM	#4
Lemmon Senior Member Join Date: December 25, 2009 Location: Rural South Carolina Posts: 445	Reloading caution I recently was reloading 9mm rounds on my progressive press. I always use a case gauge to check the round after it comes off the press to make sure it will fit my pistol. Better to check now than later. I found that 380 rounds will go through the progressive press easily and load. Glad I use the case gauge. It quickly let me know that I had loaded some 380's in batch which I immediately pulled the bullet to keep from making a dangerous mistake... Lemmon from Rural South Carolina

February 9, 2013, 03:44 PM	#5
higgite Senior Member Join Date: October 21, 2010 Posts: 1,025	When you say .380 and 9mm cases are the same diameter and same rim sizes, which 9mm cartridge are you talking about? Obviously not 9mm Luger.