Home Forums Hunting & Shooting Ask The Gunwriters Why did US Ordiance choose 0.308 groove size

I have wondered why the US Army chose 0.308 inch size for its new smaller bore military rifle in the late 1880's when several European developers used a 0.311-.313 bore size ie 7.62x54R,7.65mmx53 and 0.303 British (and later the Japanese 7.7mm).

No one can argue the inferior performance of the European (31Calibers) bore size relative to the US adopted 0.308 bore size. All of these military calibers have served well.

Could it be the difference between metric and English system of measurement even though the British used 0.303?

Could it have been American pride to use something different? Can anyone think of a technical reason to use 0.308
in preference to the European larger bore size?

Can we hear some discussion of this subject?

Centex Bill

The American 30 caliber was already standardized at .308" going back to the .30 wcf. Would be my guess.

The military adopted the .30-40 Krag before there ever was a .30 WCF

American Rifleman did an article about the decisions of arriving at the 308 diameter! I don't remember the reasons, but they did a good job on their choice!

Exercising 20/20 hindsight, it is hard to understand why the U.S. Army selected the Krag and the rimmed 30-40 cartridge when the there were already military Mausers in 7x57 and 7.65x53 in play.

I ve heard that both ways. The Krag may have came along first. Which would bring back the question why .308"?

Hmmm. Just for clarity:

The US Army selected a bore diameter of 0.300 inches. The groove diameter is 0.308 inches.



--Bob

Beat me to it.

I stand corrected. Then why the GROOVE diameter difference from the European rounds? It would appear that the design of all of these rifles and cartridges occurred in the late 1880's. The 303 Brit was in late 1880's. The 1889 Mauser was chambered in the 7.65x53mm and the 7.62x54R was chamber in 1891 Russian Mosin Nagant.

The US 30-40 Krag was chambered in the 1892 Krag. All of these rounds were developed in a 5-8 year period.

My basic question is: WHY DID THE U.S. ARMY GO A DIFFERENT GROOVE DIAMETER THAN EUROPEAN DEVELOPMENTS?

Centex Bill

Don't know why but I'm glad they did.

Because the U.S. Army is not gay.

I mean, we could take this a step farther and wonder why some of the Continental powers followed by the US moved away from the 8mm that Germany and France got the smokeless ball rolling with? I don't know if 8mm trumps .30 but Col. Askins spent a lot of time saying it does. I know .308 and .311 would be a dead heat if bullet selection were the same. I guess .300 sounded catchier to America while .303 sounded cool to some Euro countries.

In the late 1880s...

With the coming of the French Lebel round in 1886; within a few years of it's adoption, and before the century ended, the military of every major nation had adopted a similar 30 caliber bore size. A few smaller nations went smaller...but a 300 .295 310 311 312 bore etc was the new norm.

The point being that all of the different rounds were essentially 30 cal within a few tiny fractions of an inch.

There was no real technical reason, the technology was the same and the ballistics were similar. Any small differences past the muzzle end were not related to the bore size, and remember they were firing round nose bullets until 1898 and later.

The small differences in bore sizes and the myriad dimensional alterations to the rounds themselves may have been done to try to avoid patent infringement, international treaties or manufacturing contracts.

Mauser may have signed the German military contract with an exclusivity clause with the stipulation that Peter and Paul would not supply the same round to potential enemies.

In spite of all the changes, the US ended up paying Mauser a lot of money for infringing on their patents relating to the Springfield Rifle and a German Ammunition maker for infringing on the spitzer bullet design and the overall design of the 30-06 round itself.

That was both before and after the war, so the patent issue was serious enough to be a concern.

It might have been a simple matter of someone in US Ordnance thinking .300" was somehow a neat sort of number, but it is noteworthy that Eduard Rubin, responsible for the development of the jacketed bullet, used that bore size for a number of trials cartridges in the early to mid-1880s. This attracted a good deal of attention in Britain and the US (and also of course in Switzerland, which adopted a round with a .300 bore in 1889). Frankford Armory received a batch of Rubin rounds in 1890, one variant of which was selected for a manufacturing run of 100,000 rounds for testing purposes.

There was a bit of development work of course, and some tweaking of bullet dimensions, among other things (.309" and .306" diameters were tried, before .308" was settled on). A "German" or "headless" (ie rimless) case was also trialled, based on the 8x57J, as was the Belgian Mauser 7.65, but the rimmed case was preferred, based on the tweaking of what had originally been a Rubin design, and the decision was made in 1892 to adopt that round as the .30 Ball.

Did they choose the 308 (30/40 Krag cartridge) in 1892 or did they choose the platform, Krag rifle, that just happened to be a 30/40 Krag?

Who invented the 30/40 Krag cartridge, I'm guessing the Norwegians? I don't know. I do know they submitted the Krag rifle for testing, along with another 50 or so rifles submitted. Certainly not all rifles were 30 caliber.

So, was it the platform (Krag rifle) that was picked and the 30 caliber part happened to come along with it?

The 303 started as a black powder / lead bullet cartridge. Could be the lead bullet and or the cordite powder.

I know the Norwegian Krags were 6.5mm. If memory serves it was the US Army that developed the .30-40 cartridge as the .30 US Army.

no one can argue the inferior performance of the European (31Calibers) bore size relative to the US adopted 0.308 bore size.

I can, and will,....... that's a flat out weird statement, made by somebody who confuses groove with bore.

Lands vs grooves measurements?

The Krag is a neat old design, l bet it would be a costly sob to produce.

The ordinance department did pick some doozies over the years didn't they. The Trapdoor, Krag,the Lee 6mm and maybe some others I can't think of know. But in hindsight they all beat pouring powder out of a horn.

As I said, just before you posted, the .30 Ball (.30/40) was developed based on a Rubin design, tweaked at Frankford Arsenal. It was developed in parallel with the Magazine Rifle trials, and rifles were submitted based on both rimmed and rimless versions before the decisions were made to go with the rimmed-case version and the Krag Jorgensen rifle.