Difference between 7.63×25 and 7.62×25

Good Point Fede,
I posted the CIP TDCC for comparison, but it is only as good as the dimensions submitted.
Maybe somebody has the original DWM drawings for the Mauser?

1 Like

Fede - thank you for that reply. CIP and SAAMI standards are very much “after the fact” for calibers designed and used for years before the inception of either of those establishments. I don’t know their criteria for establishing standards for a cartridge a full Century after its development and use, or for establishing new names for older cartridges.

I have measured a large selection out of my combined collection of about 800 of the 7.62/7.63 x 25 mm case type, and found as much variance between cartridges of the same nomenclature as I have between cartridges of the two different names.

I admit that the among all the various countries, factories and eras of production among these two cartridges there is not 100% safe interchangeability, not only because of differences in the realm of pressure/velocity, but also in simple case versus chamber dimensions. I only own two pistols in that caliber, a Chicom Type 54 (Tokarev) and a Czech CZ vz 52, but can report about a 15 - 20% failure of Fiocchi 7.63 Mauser cartridges to fully enter the chamber of the Type 54, despite the high quality of the Fiocchi ammunition. The same cartridges fully chamber in the Czech Pistol. Unfortunately, I haven’t owned a Mauser “Broomhandle” pistol since 1971, and don’t recall ever trying various specimens of the cartridge under both names in any of those pistols. I also only tried Fiocchi ammunition, because I did not want to use specimens from my collection, and that was the only 7.63 mm Mauser ammunition I had at hand. Once again, certainly not a scientific test with only one brand of cartridges and one single specimen of each pistol used.

Just my observations on this question. I do not, under any circumstances, suggest using ammunition known to be of the Tokarev variety in any Mauser, Astra, etc. broomhandle-style pistol, due to the high end pressures of some (perhaps most, ¿Quien sabe?) Tokarev ammunition.

John Moss

2 Likes

Mauser 1937 drawing:

2 Likes

For comparison, the Albom kontruktsij patronov gives the bore/groove diameters of the “cartridge for pistol model 1930, designed by Tokarev (TT)” as 7.62 mm and 7.92 mm. Alas, the quality of the copy I have is not sufficient to decipher the tolerances.
The Soviet length of twist (German Drall) is given as 240 mm and the maximum bullet diameter surprisingly “only” 7.85 mm. Other Soviet maximum cartridge dimensions:
neck diameter 8.37 mm
case length 24.7 mm
length to shoulder 19.53 mm
Readers may compare this to the Mauser drawing kindly supplied by Fede.

Edit: The Tokarev bore and groove diameters are the same as those used for the Nagant (Russian Nagan) revolver and the 7.62 mm rifle.

2 Likes

Thanks for the further information, Fede & Joachim. I am not technically-minded, unfortunately. Regarding bullet diameters, all I can say is that Fiocchi 7.63 Mauser ammunition shot very well in my Czech vz 52 pistol, and at the time, I was a good enough pistol shot to judge accuracy in a pistol from shooting it. I did my little experimenting with measuring of cartridges, and while I recall the general conclusions of the measurement tolerances, I stupidly did not save the results, as they were pretty much scribbled notes, and seemed to be able to be summed up as I mentioned, as much tolerance spread within each cartridge type as between the two cartridge types.

If I find time, I may do a much narrower measuring session again.

I did know that the Russians maintained the same bore and groove diameters in the TT30/TT33 pistols as existed in the Nagant revolver and the Mosin Rifle. I always figured that was why the .30 Mauser cartridge as made in Russian was re-defined as 7.62 rather than 7.63, simply to keep the nomenclature uniform. That was probably an over-simplification of the reason for the designation “7.62 mm.”

John Moss

3 Likes

The dimensions of the two cartridges are the same.
Comparisons of parameters from the provided drawings.

2 Likes

About shoulder length size L1 - (C.I.P.)
Here is an example of 7.62 x 39 different manufacturers.

1 Like

Peak pressure of powder gases. 7.62x25 TT

2 Likes

A question, the answer for which I may have simply missed:

Why is the .30 Mauser named “7.63mm”?

1 Like

Why is it named .30 Mauser?

1 Like

Mauser designed pistol, evolved from the Borchardt, .30 caliber is a common reference point, used for simplicity.

I understand the Russian caliber numbering system, but why/how did 7.63 come about?

1 Like

Your may remember that the given caliber designation of any caliber is soleyly routing from the inventor’s name.
If my memory does not betray me, by 1896 there was no caliber around that officially was called a 7.62mm.
Defacto your question must be: why all 7.62mm are not being called 7.63mm?

1 Like

I guess the quick answer the 7.63 mm Mauser is a German-designed version of the 7.65 mm Borchardt cartridge, hence the original name is expressed in the Metric System. When the cartridge got popular in England and the United States, both “inch-measurement countries,” the name of the cartridge was converted to the inch measurement of .30 caliber (3/10ths of an inch; 0.299"), from the metric system.

Regarding the 7.65 Borchardt Cartridge and the 7.63 Cartridge, in later versions, at least in the United States, identical cartridges, they were originally sold as different cartridges, therefore with two different designations, that are actually virtually the same.

I would argue that the statement you opened with, “Mauser-designed pistol, evolved from the Borchardt,” is not correct. The Borchardt and Mauser designs are totally different. A more correct rendition of your statement would be "Mauser-designed pistol CARTRIDGE, evolved from the Borchardt CARTRIDGE. Sorry to be a nitpicker, but the difference changes the complete meaning of the statement.

John Moss

3 Likes

Thanks a lot for your answers,dear friends!

Yea, I was thinking catridges but Borchardt/Luger sort of pushed its’ way in, but in my defense I was somewhat sleep deprived.

Nice job of avoiding answering the actual question.

Badger - try rephrasing your question. I thought that I had answered it. “Why/how did 7.63 come about?” How does any caliber and its designation come about? People at the Mauser factory designed the C’96 Mauser pistol, nicknamed “Broomhandle Mauser” today among American collectors, and decided to use the 7.65 Borchardt cartridge case for its first caliber. The Borchardt was finalized by DWM who chose to call the cartridge the 7.65 mm Borchardt. Obviously, Mauser wanted to have its own designation for the caliber of its then-new pistol, and decided to call “their” cartridge the 7.63 mm Mauser.
The difference between 7.65 mm and 7.63 mm is almost imperceptible, both rounded to what is called .30 caliber in inch measurement. The people marketing the product have the privilege of calling a product whatever they want to, as long as there are no copyright infringements.

Seems pretty simple to me, but again, I answered the question as I understood it. If that is not the answer you were looking for, then try asking the question again formed in a more complete manner to make clear precisely what it is you want to know

I don’t think anyone of this Forum would waste his time with writing any answer to purposefully avoid answering the actual question, which is what your last entry intimates

John Moss.

2 Likes

BadgerJack,
You need to realize that it is not the first topic on this forum where some very knowledgeable member took the time to write nice posts to answer to your questions and you seem to have your own point of view and don’t care of the answers and explanations gaved to you! Don’t ask questions if you don’t want a different point of view than yours!!

1 Like

Some questions can not be answered. That was my answer…

Dude, I was asking a serious question that I was hoping to actually get an answer to, which had NOTHING to do with my point of view.

“I do not know” would be a valid answer. Why some people chose to give a non-answer I do not understand, as EOD did, in my opinion, and I was not directing that comment to anyone else.

So please do not jump down my throat when I am simply seeking valid information, and am disappointed by a non sequitur answer.