Loading Data - 8mm Nambu?

[cuzinbruce]

Hi,
Wondering if anyone could point me towards some loading data for the 8mm Nambu. I found an old Hensley & Gibbs 116 mould, cleaned it up and cast some boolits with it. They look great, now I am looking for some loading data. Any help, much appreciated.
Thanks,
Bruce

[Swagerman]

From my sixth edition of Handloader's Diegest by John T. Amber, we have these loading notes on the 8 mm Nambu.

The only powder that is still widely know is Unique at 3.8 grains, this moves a H&G 116 grain #31950 bullet at 1,000 fps velocity.

Factory ammo from Japanese military sources average 1,066 fps velocity...so, that Unique load is pretty close.

If you can find some old out of production Trap 14 powder its 3.7 grain with no velocity figure quoted.

What are you using for brass cases?


Hope this helps.


Jim

[NVcurmudgeon]

It's been forty years since I loaded 8 mm Nambu, so I won't try to remember loading data. Don't know if anybody makes Nambu cases, but in the olden days we go by with shortened .38 Super cases. They bulged plenty, but with moderate loads never blew out.

[MakeMineA10mm]

I actually scored some 8mm Nambu cases from Midway when they made a short run of them back in the late 70s / early 80s. I've found through measuring that 40 S&W will make dandy Nambu cases, IF they stretch a bit when necking them down. (I haven't tried it.) If they don't stretch enough to get appropriate case length, 10mm cases could be substituted, and then trimmed to the correct length.

[cuzinbruce]

Thanks Swagerman. I expect to buy brass from Huntington's and dies from CH. I have plenty of Unique so that should work.
When I get the dies, I will try making the cases.
Bruce

[Swagerman]

Can't remember the year but back in the 50s I bought an 8 mm Nambu from a pawnshop for $25.

It had an original holster with a small cardboard box of 8 mm cartridges, had Japanese markings on it. All that was in pristene condition. Most likely some WW-2 south pacific verteran pawned it.

Shot a few rounds and lost interest rapidly in shooting it any further. A 9 mm was much more accurate.

Good luck with yours.

Jim

[Johnch]

If a 40 S&W case is a touch to short
Try a 357 SIG case
When blown out they are a touch longer than the 40 case

I know because I shot a few 357 Sig's out of the 40 barrel on the Sig 229

John

[TAWILDCATT]

if my specs are correct the nambu case is .410 at the base.I bought a Lee bullet dieand pushed th .40 cal smiths thru.I dont have a sizing die soo drove case in chamber.the gun is not complete.but I wanted to try the case making I had 2 nambus one remade to a blown out 30 luger chamber.so could shoot luger and then reload properly.both guns like new wish I had them now.:coffee: :coffee: :Fire:

[kywoodwrkr]

Haven't loaded any Nambu since early 70's when I bought forming die set and reloading dies and reloaded ammunition for a friend who had the Nambu presented to him by his body guard when he left/escaped from China during WW2.
He flew with Flying Tigers (II), after Chennault's Flying Tigers, and his body guard presented him with the Nambu which was supposed to have, written in Chinese on the woodwn grips, that any Chinese citizen was to give his or her life to protect him from capture by the Japanaese.
He had not fired it since it was given to him until I made him some ammunition.
I later bought and gave to him a box of the Midway ammunition.
Thought Graf & Sons had Nambu brass as well as jacketed bullets.
I found 40 S&W and the 357 Sig brass to be larger in the base than the Nambu round produced by the forming die set which required 25/30/32 Remington cases.
Lyman 31950, a C&B bullet, for the 31 cap and ball pistol was used for casting usable bullets.
DaveP kywoodwrkr

[floodgate]

kywoodwrkr:

"Lyman 31950, a C&B bullet, for the 31 cap and ball pistol..."

Actually, according to Ideal Handbook No. 9 (1897), where the full array of Ideal bullet moulds was first listed, #31950 "...is the factory .32-40-98 M[arlin] short range [bullet]." Good that it also worked in the 8mm Nambu, as well as the .31C&B's; a versatile boolit indeed, but I doubt we'd be able to raise 25 bids for a Group Buy...

floodgate

[onefunzr2]

I run 357SIG brass cases through my Redding 8mm Nambu sizing die. I chuck them in my mini lathe and shave off that part of the case body just above the extractor groove that cannot be squeezed down to the Nambu dimension of my chamber of .4085". Then I trim the neck to .855".

HDS cases (made by Starline) give 15.6gr of water case capacity. My reformed Speer 357SIG cases yield 17.1gr. FWIW