8mm Nambu Cartridge Conversion

[sheepherder]

Originally Posted by Sieger

Please also note that the Japanese were known to prefer short ogive bullets, leaving more of the bullet to actually ride on the lands.

Here's a comparison of the two Nambu cartridges I have plus my conversion (pic attached)...

The lead-bulleted cartridge is headstamped 'W C C 6 6' and was bought from a cartridge collector at a gun show in the late 70's/early 80's for $1.00...Ed's cartridge has no markings...Mine is the 40 S&W conversion...

Lead - .407" rim .376" base .844" case 1.240" OAL .320" bullet
Ed's - .412" rim .411" base .861" case 1.244" OAL .320" bullet
Mine - .413" rim .410" base .866" case 1.246" OAL .321" bullet

The lead-bulleted cartridge has a pronounced semi-rimmed configuration...I have no idea what it actually is (original case)...I am measuring the bullet at the case mouth, it may be larger inside the neck...

[Sieger]

Originally Posted by sheepherder

Here's a comparison of the two Nambu cartridges I have plus my conversion (pic attached)...

The lead-bulleted cartridge is headstamped 'W C C 6 6' and was bought from a cartridge collector at a gun show in the late 70's/early 80's for $1.00...Ed's cartridge has no markings...Mine is the 40 S&W conversion...

Lead - .407" rim .376" base .844" case 1.240" OAL .320" bullet
Ed's - .412" rim .411" base .861" case 1.244" OAL .320" bullet
Mine - .413" rim .410" base .866" case 1.246" OAL .321" bullet

The lead-bulleted cartridge has a pronounced semi-rimmed configuration...I have no idea what it actually is (original case)...I am measuring the bullet at the case mouth, it may be larger inside the neck...

Hi,

It might just be an optical, but it looks like the thickness of your rim base is substantially thicker than Ed's original. This causes the extractor damage mentioned previously. What is the original rim base thickness? What is your rim base thickness?

Sieger

[sheepherder]

Originally Posted by Sieger

Hi,

It might just be an optical, but it looks like the thickness of your rim base is substantially thicker than Ed's original

Yes, it's an optical illusion. The case is tilted slightly away (you can see the primer if you look close). That plus my filing of the edge is only slight on this one. Ed's rim is an indicated .045"; mine is .046". I aim for .042" but it's difficult to measure. Difficult to machine too, as I can't get any measurement without removing the case from the setup. I have to rely on a dial indicator. I'm working on a better way to index the case between the live center and the parting tool.

By the time I get it fully sorted, I'll have lost interest and gone on to something else...

Originally Posted by Sieger

I was looking for the bullet length, not the cartridge O.A.L.

Ah...I have no idea...

[sheepherder]

There's a couple of loads for the 8mm Nambu in another thread at -

http://forum.lugerforum.com/showthread.php?t=31825

Several articles there, couple of different powders & bullets...I added one from a 1981 article, might be the best to start with...

[rhuff]

I believe that there are also some loads for 8mm Nambu in a past edition of Handloader Magazine. Mike Venturino writes articles for that magazine, and he owns and shoots a Nambu. If I recall correctly(always a real question), he is casting his own bullets. I will see if I still have that edition. Usually, if the magazine has no information of interest to me, then I discard it after reading it.....otherwise I end up with waaaaay too many magazines.

[Sieger]

Originally Posted by rhuff

I believe that there are also some loads for 8mm Nambu in a past edition of Handloader Magazine. Mike Venturino writes articles for that magazine, and he owns and shoots a Nambu. If I recall correctly(always a real question), he is casting his own bullets. I will see if I still have that edition. Usually, if the magazine has no information of interest to me, then I discard it after reading it.....otherwise I end up with waaaaay too many magazines.

Hi,

Mike and I have spoken more than once, over the years.

For me, his articles are quite good regarding the history of a particular firearm and his wife is a fantastic photographer, but his articles lack the depth of precision I particularly enjoyed from, say, Ken Waters.

On the laughable side, in one of the articles he wrote on military pistol handloading, he, admittedly, couldn't get his 9mm Luger to shoot without constant jamming. Again, obviously, he has no depth of experience with nor understanding of this particular firearm's design, yet, he writes as an "expert" anyway.

He now, by the way, has proclaimed himself an expert on the military firearms of the two World Wars. Well, good luck to him, but from those of us who have been precision handloading for military firearms for decades, quite a bit of depth is lacking in his work, here, as well.

It seems like the old timers have past into history, pretty much the same as everything else has now a days.


Sieger

[rhuff]

Originally Posted by Sieger

Hi,

Mike and I have spoken more than once, over the years.

For me, his articles are quite good regarding the history of a particular firearm and his wife is a fantastic photographer, but his articles lack the depth of precision I particularly enjoyed from, say, Ken Waters.

On the laughable side, in one of the articles he wrote on military pistol handloading, he, admittedly, couldn't get his 9mm Luger to shoot without constant jamming. Again, obviously, he has no depth of experience with nor understanding of this particular firearm's design, yet, he writes as an "expert" anyway.

He now, by the way, has proclaimed himself an expert on the military firearms of the two World Wars. Well, good luck to him, but from those of us who have been precision handloading for military firearms for decades, quite a bit of depth is lacking in his work, here, as well.

It seems like the old timers have past into history, pretty much the same as everything else has now a days.


Sieger

I do not know the gentleman(Ventrino) personally, and have never spoken with him on the phone. I do know that the first Luger that he purchased was a 30 Luger caliber, and he could never get it to run correctly. He sold it, and purchased a 9mm Luger. Apparently, he can get this Luger to preform reliably.

I was just trying to help out with some additional loading data for the Nambu. ANY handloader that is willing to take a loading "recipe" off of the INTERNET(non-factory powder company load) and use it without double checking it, is a fool as far as I am concerned. Perhaps I am overly cautious, but I still have all of my fingers, and both eyes!!

[sheepherder]

Originally Posted by rhuff

I believe that there are also some loads for 8mm Nambu in a past edition of Handloader Magazine. Mike Venturino writes articles for that magazine, and he owns and shoots a Nambu. If I recall correctly(always a real question), he is casting his own bullets. I will see if I still have that edition. Usually, if the magazine has no information of interest to me, then I discard it after reading it.....otherwise I end up with waaaaay too many magazines.

I drag mine over to the local gun club. Someone will read them. I've seen Venturino's byline occasionally over the years, but don't recall whether I thought he was full of hot air.

I made two new 'mandrels' for the 40 S&W cases yesterday, one for the swaging and one for the tailstock chuck. I wasn't happy with how the rim thinning was going. I went back over my cases and there was a tendency for the thickness to slowly increase as I went through more & more cases. The swaging process in the 30-30 die was leaving a small ridge on the edge of the rim, throwing my 'zero' off. A new primer-centered ram fixed that. I also replaced the Nylon mandrel with a brass one. A quick test run showed marked improvement. I'm going over the other 20-odd test cases to correct the ones that got too thick.