30-06 and other military cartridges

[t-train]

I have a random question about the 30-06: why is the case so long!? If you compare it to other contemporary military cartridges, all the others are shorter, some more so than others. Take the 7.62 Russian for example, developed about 15 years before the 30-06, and yet much shorter. Then look at the 7 and 8 mm Mauser, and .303 British. And all modern military cartridges follow the same pattern; meanwhile the US adopted a long-cased cartridge for how many decades (albeit a GREAT round), and finally caught on to short cartridges with the 7.62x51 (.308).

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[Patrick Chadwick]

why is the case so long!?

Presumably to fit the powder in to provide the intended energy at the appropriate filling level to keep the chamber pressure below a prescribed maximum.

I am not joking - the powder used in developing the original 1903 case may have had very different characteristics to modern powders. And the case capacities of the Swiss 7.5 and Japanese 7.7mm cartridges are only about 10% less. The Lebel 8mm is almost as large - but very much fatter (as is the Russian). The volume (determined by the powder) and the maximum diameter compatible with a "rimless" near-parallel sided design for a compact magazine (like the Swiss) will have led to the length.

[browningautorifle]

All these cartridges are designed that way. To hold the propellant to suit the demand prescribed for the cartridge.

[CINDERS]

A good read on the study of ballistics is the Bullets Flight By Mann ABE books are a source copies can vary in price but he did conduct some very good experiments and photographed the results I have only graze read my copy but he lined up 200yds of either canvas/paper targets all lined up perfectly and fired a round from a mounted rifle to show the oscillations before it stabilized in flight pretty good book.

Post script - also from memory again that the projie oscillated around its path of flight (Lets not forget he was doing this pre 1900) he had a cross on every one of those targets and it showed the bullets strikes differing along the longitudinal axis (not yaw) really a great read I must say he did all sorts of stuff with rounds.

[RCS]

Over the past few years, the CMP has sold on auction, a number of Mann test rifles, calibers being 7,62x51 and 30-06. Most of these actions are M1903A3 with short very heavy bull barrels, the stocks are cut-off in back and front. A fixture is use to fire the rifle. These make excellent bench rest and long distance rifles when restocked and are scope mounted. Maybe someone can find a photo of a Mann test rifle from the CMP auctions

[browningautorifle]

Here's an article with pics... http://www.odcmp.org/1001/mann_inc.asp

[RCS]

Thanks Jim, for posting the article on the Mann actions & barrels. Some collectors just leave them alone as a collector item while others restock them, remove the collar and mount a large power scope. They are quite accurate when built-up

[browningautorifle]

I saw one once I thought was one of these, turned out it was a .30 MG barrel. 1919 barrel modified for the action. What a club...be very stiff though.

[RCS]

I have also seen the Browning Model 1919A4 barrel used on bolt actions too. These barrels can be used with a bushing threaded inside for the 1919 barrel and outside for the Model 1917 receiver. Often the barrels will have a liner which is very difficult to cut with a chamber reamer. After all the work to fit such a barrel, often they are not that accurate and some use lead bullets.

[browningautorifle]

They are what they are after all.