Caliber naming convention is 45/70 ?

[davidtdm]

I just read the "What's your Quigley.." post. What does the 70 in 45/70 mean. I assume the 45 is .45 caliber? Is the second number a date designation as in .30 06. .30 caliber made in 1906.

Just curious

..Dave

 

[Atticus]

70 grains of powder.

"The .45-70 cartridge was first introduced with the Model 1873 single shot Springfield. Several model changes were made from 1873 through 1889, relatively minor differences being the type of sights, modified and improved breech-blocks and changes in stock furniture.

The first long range tests were made at ranges of up to 1,500 yards on the Springfield Armory test range at Long Meadow, Massachusetts. These tests compared the long distance shooting and penetration performance of the .45 caliber trapdoor Springfield and the .45 caliber Martini-Henry rifles.

The Springfield rifle weighed about 9.6 pounds, had a rifle barrel 33 inches long with a bore diameter of .450-inch, three grooves and a right hand twist and groove depth of .005-inch. It fired the then standard Service round consisting of the 405-grain bullet in the rimmed straight case 2.1 inches long with 70 grains of black powder giving a muzzle velocity (MV) of 1,350 feet-per-second (fps). With the same weight of bullet and a charge of 85 grains of powder, the MV was 1,480 fps. "

 

[goon]

The "70" is the powder charge in grains of black powder.
Same with rounds like 44-40, 38-55, etc.

 

[mete]

Proper black powder designation is caliber, grains of powder and bullet weight. So - .45-70-405 . The military also used 45-70-500 ,and 45-55-405 for carbines.

 

[Glamdring]

IIRC the 45-70 was originally loaded with a 500 grain bullet. The 400 grain bullet was developed for the carbines.

 

[Doc]

and boy are they fun to shoot

here's some photos

 

[Mike Irwin]

And, just to throw some more confusion into the mix, you will very occasionally see a FOURTH number in that long string -- the case length.

Any number of companies at the time would offer, for example, a .45-90. Sometimes the only sure way to tell the different cartridges apart was by the case length.