38 Special formed into 30 Luger or 8mm Nambu

I have a 38 Special (R-P 38 Spl) formed and loaded into 7.65 Parabellum (or so I am told). Why? Is it economics or something else?


We need some case dimensions.


It’s perhaps posing as an 8m/m Nambu? JG

Vlad - probably the only useful dimensions will be the rim diameter, the case length and the bullet diameter at the very mouth of the case. The approximate height of the shoulder might help as well, although that is always hard to measure. If you do, be sure to tell us if you are measuring from the case-mouth down, or from the head up. The base dimensions and those below the shoulder will not be much help, since they will probably be .38 special, unless this case was reloaded one or more times in its current configuration, in which case it will be fire-formed a bit. I doubt that it has, looking at it.

It appears the rim was left full size, which is unusual. Dimensions will help us there. It could be .30 Luger - .30 Luger ammo is expensive, although it is hard to think that since it is available, and cases are now available, that this would have been done recently. The R-P headstamp however, while current, has been around a long time now.

It might also be 8mm Nambu. Making 8mm Nambu from .38 Special cases was a pretty common practice until so much commercial 8mm Nambu brass became available. It was even done years ago commercially. I used to buy them occasionally to shoot one of the Type 14s in the auto pistol collection I had at the time.

One reason I doubt your round has been reloaded in its current configuration is that if 8mm Nambu, the cases usually split quite badly on the first firing. (Please not that I said “reloaded IN its current configuration,” NOT "reloaded TO its current configuration). The commercial source I had even advertised that, so there would be no misunderstanding. It was not a particularly dangerous happenstance, but meant there was no salvage on the cases, of course.

Please do provide the dimensions, especially rim, case length, and bullet diameter, and maybe we can tell what it is.

Despite the cartridge in question (and it’s measurements) .38 Spec. is an often used base for making 7.63 Mauser out of it (and likely the 7.65 Para).

EOD - probably true, although in years of picking up ammo, I have never seen a .30 Luger round made from .38 Special. I have seen a .30 Mauser round - I have one from Argentina that was supposedly a factory experiment, although I doubt that. The most interesting thing about it is the odd bullet that is in it.

One is probably better served for case strength by making .30 Mauser out of .223 brass - yes, it does work and you won’t have a case-head separation, that’s for sure. I wouldn’t do it because frankly, these days, there is little or no reason to do either caliber from .38, as thanks to companies like Starline, you buy good quality, correct brass for most all of these calibers, and at prices that aren’t horrible, considering the price of brass these days. After WWII, there was reason - lots of souvenir guns, in our country anyway, and no ammo. Even the 9mm Para was commonly made out of .38 Special brass - I have several examples of that in my collection.

The rim on the cartridge pictured still bothers me for any auto pistol round. I recall the 8mm nambu I used to shoot had the rim turned down to fit the breech face. Of course, like everything for me now, that was a lot of years ago!

That round in the photo looks semi rimmed, aren’t the .30 Luger and 8mm Nambu both rimless rounds?

Falcon: Yes, they’re rimless, but (at least in the case of the 8m/m Nambu) when brass is formed from .38 Special the body is so undersized the finished case is semi-rimmed since the rim is of proper dimensions but the case body isn’t. It’s not ideal case forming, but in an emergency it works, or so I am told. JG

Case length-22mm
Bullet diametre-8mm
The shoulder starts 17mm from the head and is about 1mm long
Case diametre is 9.5mm below the shoulder and 8.6mm above the shoulder
Here is the headstamp

I think it is just what J. Gill and I thought almost simultaneously, judging from the time on our two postings. It is, in my opinion, an 8mm Nambu. Depspite how the rim looks, the diameter would work (list rim diameter for 8mm Nambu is 10.45-10.55mm. Case length is right too, although not a determining factor in a bottle-necked cartridge, with Japanese rounds running from around 21.2mm to as high as 21.9mm, and in this case, within similar specs to the case length of a 7.65 Par (.30 Luger) at around 21,50mm. It is the bullet diameter here that tells the story, I think. Even the rim diameter is not out of the question for 7.65 Para, that normally has a maximum rim diameter of 10.00mm. Only 0.05mm over. The shoulder, too, is very similar on both the 8mm Nambu and the 7.65mm Para - I had not even relaized how similar to now, checking them against each other. The biggest differences in the two rounds are the bullet diameter and the head diameter, but in this case, the head diameter is very small due to it being a .38 special case.

Frankly, aside from the 8mm lead bullet, it is much harder to tell than I had thought, and the fact is, this round might chamber and fire in either caliber, due to its smaller .38 Special head size. I am not sure - the round would have to be measured at many spots, or dropped into the chamber of pistols in both calibers.

Interesting, at any rate. I still vote for 8mm Nambu because of the bullet diameter, altough as I was writing this answer, I almost talked myself out of it.

Ray, let’s mix British, Metric and Inch caliber nomenclature and call it the 8x22mm/.38 Special wildcat. Just kidding! Don’t boot me off the Forum.

Here in Europe they are not uncommon.
Usually then the rim is turned down and an extractor groove is added.

As a Nambu shooter and case former for 40 years can say hands down that cartridge will not chamber in a Nambu. 38 Special rim averages .436-440" diameter. Nambu .410-.415" My Nambu bolt face is measures .414". Yes the Nambu has a bolt!


Hey fellas, don’t rule out the possibility that it is simply a wildcat. There are several wildcats made by necking down the 357 Magnum and 38 Special case to 30 caliber. The 30 Picra, 30 Hoskins, 30 Paxton come to mind. Some are necked all the way down to 22 caliber such as the 22 Sabre Jet and the 22 Ackley.

I’m not saying that Vlad’s cartridge is one such wildcat. I’ve not seen one that short. I myself think it is an attempt to make shooting ammo for a pistol. But never underestimate a wildcatter.


Gourdd - that rim on the cartridge in question, despite the look, has according to its owner been trimmed to 10.05mm. If it won’t work in an 8mm Nambu, it is because it is undersized, not oversized. That might interefere with extraction - just not sure. Wish I still had a Type 14. Not a bad pistol despite all the negative print it has received over the years. I have had about fifteen of them over the years, and even one made in Showa 20 (1945) while rough around the edges was perfectly serviceable. The early ones are as well made as any fine commercial Colt or S&W. 10.05 mm equals about 0.396", and now that I have converted it, it appears to be more compatible with the rim diameter of the .30 Luger (7.65mm Parabellum). Just a very small amount oversize from what is generally considered .30 Luger maximum, around 0.393". Still, his round has an 8mm bullet??? Back to the drawing board guys. Now I am not sure which caliber it is.

Vlad - do you have a .30 Luger or 8mm Nambu caliber gun that you could strip down and try the round in the bolt fact and chamber? In lieu of .30 Luger, a breech face (or, yes Gourd, my friend) a bolt face for .30 Mauser or 7.62 Tokarev would work as well to see if the rim diameter is o,k. for .30 Luger, as the rim specs on the three cartridges are similar. All use what is called by some the “basic 10mm head.”

By the way, Gourd, have shot several hundred 8mm Nambu rounds made from .38 Special cases - rim turned, of course, and they shot perfectly well, with perfect functioning although every case split from the neck far down the case. The best case to make it from was the .41 LC, I am told, but too expensive for a commercial venture after WWII. I have seen a few rounds from time to time made from that case, but it is a moot point today, with 8mm Nambu brass readily available. Much better for the collector, since it is all properly headstamped.

I have nothing which shoots .30 Luger or Nambu, and my only Tokarev WWII bring-back is buried somewhere in the house, have no clue where.

Just another thought what does the bullet measure? Should be .320-.323. The bullet in the picture looks like the right shape. The only lead bullet that works flawlessly in my pistol comes from my H & G mold.