8mm Nambu Cartridge Conversion

[sheepherder]

Originally Posted by rhuff

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.

I'd be interested in that data from the Handloader newsletter.

I hope that anyone who reloads knows that older data is only relevant to powder manufactured in that particular time frame (and it should be dated). The chemical composition changes without notice from the manufacturer and the burning rates, charges, even physical appearance change as well. Older data may no longer be correct.

Even loading data for the two most common powders, Bullseye & Unique, have changed over the years.

I would caution anyone using the data in any of the articles in this thread or the other one view it with skepticism.

I plan on using only the lower [minimum] loads and then only one or two rounds, to get a feel for how they shoot.

[Sieger]

Originally Posted by sheepherder

Do you recall what part they considered 'weak'???

I thought the opening at the rear under the cocking knob was odd; and the inability to get a feeler gauge in the receiver to measure headspace is annoying...It's also somewhat distracting to pull the trigger and see the trigger bar emerging from the bottom of the receiver...

I was particularly interested in the barrel itself, and the almost exact similarity to the 120mm 30 cal Luger 'pencil' barrel...I am tempted to try to find an old shot-out Nambu barrel/extension and drill & tap it for a 30 Luger 'pencil' barrel...

Hi,

I don't know what the armchair experts were commenting on, but a WAG would be the lockup, specifically, the locking block.

The Nambu is a much heavier pistol than a Luger, and its parts don't look weakly designed to me.

Your thoughts?

Sieger

[Sieger]

Originally Posted by sheepherder

I'd be interested in that data from the Handloader newsletter.

I hope that anyone who reloads knows that older data is only relevant to powder manufactured in that particular time frame (and it should be dated). The chemical composition changes without notice from the manufacturer and the burning rates, charges, even physical appearance change as well. Older data may no longer be correct.

Even loading data for the two most common powders, Bullseye & Unique, have changed over the years.

I would caution anyone using the data in any of the articles in this thread or the other one view it with skepticism.

I plan on using only the lower [minimum] loads and then only one or two rounds, to get a feel for how they shoot.

Hi,

I believe that all loading date needs to be addressed skeptically, not just the old vs. new thing.

By the way, if you get on just about any of the major powder manufacturer's sites, you will find that they claim just the opposite; that being, that their newer powder burning rates are exactly the same as their older powder burning rates. Well, reality must fall somewhere in between these two opinions.

As for me, I always start with the lowest load and work up until I either find an accurate load or pressure signs appear. The first "pressure sign", with a Luger, is when the load starts outruning the springs and jams start occurring. Breach block slap is a very dangerous pressure sign, and needs to be avoided!

Just some thoughts.


Sieger

[sheepherder]

Originally Posted by Sieger

By the way, if you get on just about any of the major powder manufacturer's sites, you will find that they claim just he opposite; that being, that their newer powder burning rates are exactly the same as their older powder burning rates.

Then they are lying out their ass.

Here's scans from two Speer reloading handbooks; the first is the 1987, the second is the 1979. I like the older manuals because the newer ones do not have 30 Mauser, 30 Luger, or 8mm Nambu at all...

Edit: Third pic is a note from the 1991 Hornady Reloading Manual on the powders they list...

[Sieger]

Originally Posted by sheepherder

Then they are lying out their ass.

Here's scans from two Speer reloading handbooks; the first is the 1987, the second is the 1979. I like the older manuals because the newer ones do not have 30 Mauser, 30 Luger, or 8mm Nambu at all...

Edit: Third pic is a note from the 1991 Hornady Reloading Manual on the powders they list...

Well, Speer and Hornady certainly have it right, but then again, they don't produce the powder.


Sieger

[Patronen]

The statements and warnings put out there about not using older loading data may stem from the fact certain powders produced today at one time were produced by different companies.

[sheepherder]

I mentioned a Lyman [cast] bullet #32362 referenced in the Handloaders Manual Of Cartridge Conversions as being suitable for the 8mm Nambu, sized to .321". I emailed Lyman about this bullet, as I couldn't find anyone who stocked it. Here's their replies -

We have only made bullet moulds. We have not sold the bullets themselves.

Unfortunately this mould has been discontinued for many years. It was last made in the 70's as a limited production item.

I don't cast...

Sieger mentioned that Nambu extractors are hard to find when they break or 'spring'. Don Schlickman makes new ones...Don had this to say -

I do make extractors but usually have the customer send me the bolt for me to install the extractor, there is no charge for this. There are to many differences in the dove tail cut dimensions that they may not be interchangeable so I can't guarantee the fit otherwise

[Sieger]

Originally Posted by sheepherder

I mentioned a Lyman [cast] bullet #32362 referenced in the Handloaders Manual Of Cartridge Conversions as being suitable for the 8mm Nambu, sized to .321". I emailed Lyman about this bullet, as I couldn't find anyone who stocked it. Here's their replies -

We have only made bullet moulds. We have not sold the bullets themselves.

Unfortunately this mould has been discontinued for many years. It was last made in the 70's as a limited production item.

I don't cast...

Sieger mentioned that Nambu extractors are hard to find when they break or 'spring'. Don Schlickman makes new ones...Don had this to say -

I do make extractors but usually have the customer send me the bolt for me to install the extractor, there is no charge for this. There are to many differences in the dove tail cut dimensions that they may not be interchangeable so I can't guarantee the fit otherwise

Hi,

Do you have contact information for him, telephone, website, etc., as I have two items I think he can help me with.

Thanks!


Sieger

[sheepherder]

Originally Posted by Sieger

Hi,

Do you have contact information for him, telephone, website, etc., as I have two items I think he can help me with.

Thanks!


Sieger

I always make my live links in red.

[sheepherder]

I thought I had posted this link earlier, but I don't see it...It is a thread from surplusrifle.com on making 8mm Nambu brass from 357 Sig cases...

357sig brass to 8mm Nambu

357 Sig hasn't made it to my area yet, evidently...Neither of my local gun shops have any ammunition or pistols in that caliber...

[Sieger]

Originally Posted by sheepherder

I always make my live links in red.

Hi,

More specifically, does he have a website?

Thanks!


Sieger

[sheepherder]

Originally Posted by Sieger

Hi,
More specifically, does he/Don Schlickman have a website?
Thanks!
Sieger

Not that I know of...If you email him, he will send you a pricesheet...But if you're looking for examples/pics, I don't know of any...

[sheepherder]

Got a couple parcels in the mail today...One included a note from Wolff that Nambu recoil springs were on 3 - 6 week backorder...

The other was a 'warranty replacement' expander/decapping pin unit from RCBS...

I've shown the old expander in the pic below along with the replacement that RCBS sent...

The actual specs as shown by my digital electronic vernier is -

Old RCBS - .321"
New RCBS - .3195"
Homemade - .319"

This seems to be a replacement for the 'new' 8mm Nambu die set rather than the older one I have - There's no provision for belling the case mouth with the decapping/expanding unit, although it looks like it would fit my old dies. It also uses the new 'headed' pins instead of the old straight pins.

My new 3-die set is still on back order.

I'm also up to 6 crunched/trashed case per 50 in the neck forming operation. Splits or cracks. None were the 'softer' Winchester cases.

[rhuff]

I sure will be glad when ALL of the gun/ammo related suppliers can get caught up and actually have some inventory. This mess has dragged on for waaaaay too long in my way of thinking.

[sheepherder]

I don't think I mentioned shell holders for the formed brass. I use the same shell holder that the 40 S&W uses (I have the Lee universal shell holder set, so mine is a #19). RCBS lists only one shell holder for the OEM 8mm Nambu cartridge, their #25. RCBS lists nothing else for that shell holder, although I'm sure other cases might fit.

My formed 40 S&W cases don't fit in the RCBS #25 shell holder. Strangely, neither does Ed's OEM 8mm Nambu cartridge - the SH rim cut is too small. It does fit in the 40 S&W SH.

Lee's Universal SH set shows the 9mm Luger and 38ACP/Super Auto using the same SH as the 40 S&W [their #19].

Just a FYI...

[Sieger]

Originally Posted by sheepherder

I ran across this powder chart for the 8mm Nambu in another forum...It was supposedly copied from the Midway site some years back...

I haven't seen anything like that on Midway now...

Hi,

Given my memory from 10 years ago or so, I doubt the Unique Powder load suggestions in your chart will even operate a T-14's action properly (hold open activated on last round).

If this is so, keep adding 1/10 of a grain, to the minimum load listed, until the action just holds open. You have then established your lower end base load, and can work up, very carefully, from there.

The gun rags have repeated, over and over and over again, that the 8mm Nambu is a sissy. Perhaps, it had to be loaded as a sissy, so that the inferior and weakly designed Type 94 Nambus wouldn't, simply, blowup.

Though it's certainly not a 9mm Parabellum, I'm not yet convinced that it needs to be a sissy when shot from a good, sound, Type 14 pistol, and would expect similar performance from it as from its European contemporaries (from which it was obviously, copied).


Sieger

[sheepherder]

The long-awaited, backordered 3-die set of RCBS 8mm Nambu reloading dies arrived today. Ordered 12/27/13, arrived 03/13/14.

There are a few slight differences from the used set I purchased on eBay. Nothing major. The expander die is separate, like my used set. The sizer die does not use the expander 'ball' like RCBS Tech Support sent me. So I'll continue to use my home-made expander die (I'll be listing this new unused die set in the For Sale sub-forum).

I have three different digital & dial calipers; they all read differently. So, the expander is either .3185", .319", or .321". Take your pick.

This set uses the setscrew locking rings. I really prefer the older split rings. Just my preference.

[Sieger]

Originally Posted by sheepherder

The long-awaited, backordered 3-die set of RCBS 8mm Nambu reloading dies arrived today. Ordered 12/27/13, arrived 03/13/14.

There are a few slight differences from the used set I purchased on eBay. Nothing major. The expander die is separate, like my used set. The sizer die does not use the expander 'ball' like RCBS Tech Support sent me. So I'll continue to use my home-made expander die (I'll be listing this new unused die set in the For Sale sub-forum).

I have three different digital & dial calipers; they all read differently. So, the expander is either .3185", .319", or .321". Take your pick.

This set uses the setscrew locking rings. I really prefer the older split rings. Just my preference.

Hi,

Years ago I experienced the same level of frustration with an RCBS set of dies for my 11mm Mauser rifle.

I finally gave up dealing with the Neanderthals and had a custom "M" Expander Die" made up. Ah, perfection, at last, was achieved!!!

By the way, having measured original, FMJ Japanese bullets from .320 to .322, I'm trying to figure out why this group of Neanderthals have given you an expander button ranging from only .3185 to .321: as the expander should be your bullet's diameter, plus a few thousands, to allow for brass snap back. Certainly, a proper expander die has got to allow for the adequate belling of the case mouth as well.

Just some thoughts.


Sieger

[rhuff]

I, personally, would not want an expander that was the same size as the bullet diameter. I usually try to achieve .003-.004in. smaller expander over the bullet diameter so as to achieve a good interference fit, and excellent neck tension. YMMV.

[Sieger]

Originally Posted by rhuff

I, personally, would not want an expander that was the same size as the bullet diameter. I usually try to achieve .003-.004in. smaller expander over the bullet diameter so as to achieve a good interference fit, and excellent neck tension. YMMV.

Hi,

For bottleneck pistol cases, even when trying to seat FMJ bullets, my experience, with smaller expander buttons, has been consistent buckling of the case necks. This, however, has not been my experience with straight walled cases like the 9mm.

Also, I've experience lead shaving when trying to seat lead bullets with tight necks.

My experience with both has been to size down only enough to allow good entrance of the bullet, with the tight part of the neck being under the bullet, so as to avoid setback upon firing.

Just my experience.


Sieger