380 Auto - .356 diameter?

Status
Not open for further replies.
RDA 226sig

RDA 226sig

Member
Joined
Mar 9, 2008
Messages
150
I ordered some Winchester 85 grain FMJ's that were identified as 380 caliber but they measure .356+ diameter at the base. All the 380 auto reloading data I have indicates only .355 diameter. I have manuals published by Hornaday and Speer both show only .355 for the little 380 Auto. Has anyone ever loaded or seen data for the 380 auto loaded with .356 diameter bullets?

I am thinking I may try to send them back because the wife isn't buying the I need a gun that shoots 38 super use up of these bullets routine.
 
I personally wouldn't sweat a thousandth. Try loading a few and see if they chamber easily. If they do (and they probably will) shoot them with happiness!

Sorry, this won't be your excuse for the Super....


Oh, and Welcome to THR!
 
Last edited:
This is actually very common...for CAST bullets. 9mm/.380 (9mm Kurtz) will fire a jacketed bullet of .355 diameter and a cast bullet of .356 diameter; similar to a .38 special/.357 shooting jacketed of .357 and cast of .358.

Have you been able to find any reliable data for these bullets? I have a few hundred cast 95 gr Round Nose (@.356 diameter), but I can't locate the data I used for it before (lost it when I moved).
 
Thanks. I will try a test run loaded with a minimum powder charge and let 'em fly.
 
Unfortunately I am still trying to find data TechAIG. These tiny cases scare the heck out of me and I prefer to follow the book with them.
 
All the books I have only list data for jacketed; but my bullets are cast. I know what you mean about being scared of these little cases.
 
Try loading .32s&w short revolver cartridges sometime.
WHAT A PAIN!!
Don't worry...you'll do fine!
 
Most .380 barrels will slug closer to .356" then .355".
Some may even go .357"!

The only thing you have to be concerned about with .356" bullets is whether or not they will chamber in your gun. If the case swells enough from the larger bullet it may not chamber.

But I would be very surprised if you have any brand of .380 pistol with that tight a chamber!

rcmodel
 
Send them back. All the manuals state to use .355. I know that when people load 9mm in cast the bullets usually jump to .356, just like a .357 jumps to .358, but... even my lyman cast book states that in .380, you must size the bullets to .355.

I would definately sweat 1000th of an inch unless you slug your barrel and know for sure. Send them back for your own safety.
 
Go take apart some factory fmj 380Auto from Win, Rem, and S&B and measure the bullet. They generally measure between .355 and 356. If factory ammo won't hurt your pistol, neither will these Win bulk bullets.

As advised above, the big issue is the bulge in the brass after the bullet is seated. The 380Auto case has a tapered wall thickness. The case wall is thinnest at the mouth and gets thicker as it goes down. So a bullet seated deep will bulge the brass more as it hits the thicker wall. With these bullets at .356, load them a little longer and they will bulge the brass less (load longer as long as they still fit in the magazine). Check them in your chamber. If they fit the magazine and chamber fully, go have fun shooting!
 
Land to land the barrel of my Bersa Thunder 380 is 0.356+ and is pretty close to 0.357. Also, I have found a pamphlet that came with my Lee reloading dies containing data for 380 ACP specifying the bullet diameter as .356.

I will start low and work my way up carefully but I feel confident with the data I have found and measurements I have made. I will post results.
 
I have got .355", .356", and .357" 9mm bullets in the same box from Berry!

Not a problem if they will chamber.

.001" increase in bullet diameter in the larger calibers is not going to change pressure enough to even notice.

Besides, it sounds like .356" is what you need to fit your Bersa barrel.

rcmodel
 
Finally got to the range and tried the .356 rounds that I loaded last week and they worked fine. Have a bit more snap than the factory loads but the cases and primers looked fine.
 
"I know of a Python that slugged out .354 of an inch."

Yup, mine does too. Verified time and again... .354".

I've been thinking about the Barnes 125-grain .357 SIG XPB.

Russ
 
I think rcmodel is correct. The variance between individual bullets frequently/usually/sometimes varies even from bullets in the same box.

regards,

:):):)
 
RDA 226sig
these tiny cases scare the heck out of me
Click to expand...

socaldan
Try loading .32s&w short revolver cartridges sometime.
WHAT A PAIN!!
Click to expand...

These statements are not exclusive of each other are they?

I have experimented with reloading 32ACP with mixed results. Despite what some Product Mfgr's claim, some powder measures/with some powders can give you fits on little bitty cases. Very tedious. Makes me wonder how those who reload .25 acp don't have neck, back and eye aches from squinting at those little bitty cases and dropping those little bitty bullets.

regards,

:):):)
 
I think you might have a faulty measuring device.

I have never measured a Hornady bullet in any caliber that wasn't exactly the diameter it said it was in the Hornady manual and on the box it came in.

rcmodel
 
I think you might have a faulty measuring device.

I have never measured a Hornady bullet in any caliber that wasn't exactly the diameter it said it was in the Hornady manual and on the box it came in.
Click to expand...


WASN'T saying they were different in the box, there different from what a reloading book calls for i.e.: 44mag is .429 , hornady bullet is .430
 
Yes, but the Hornady book calls for .430" bullets.

That's why we should not use generic loading data for some other brand bullets.

And it's got even more critical recently with things like solid copper bullets, VLD bullets, and other exotics that don't behave the same as conventional bullets.

rcmodel
 
true.
i have 4 reloading books and a hand full of paper back books
i dont have a hornady book

i dont feel 1-2 thousand is too much to worry about , like loading for an 30cal sk or ak barrels, some i think are from .308-.312

it has also got critical do to buying what is on sale
 
I don't have it in front of me but I am almost positive the Lee book shows the bullet diameter as being .356 for all their data.
 
Status
Not open for further replies.

Similar threads

3
  • Locked
.356 diameter for 9mm plated bullet?
Replies
5
Views
958
BAGTIC
B
R
  • Locked
38 auto .356 diameter 130
Replies
3
Views
312
Walkalong
Walkalong
M
  • Locked
.357sig & .356 plated bullet question
Replies
4
Views
1K
mousegun380
M
GotHim
  • Locked
Hoping these .356 bullets work in 9mm during shortage
Replies
21
Views
2K
blue32
blue32
C
  • Locked
.38 super .356 or .357
Replies
11
Views
2K
Clifford
C
Back
Top