RIFLE-BARREL STEEL, .30 CALIBER.
82
No. 7391.
Marks, M 3 C.
Exterior diameter, ".466.
Interior diameter, ".300.
Sectional area, .10 square inch.
Gauged length, 3".
From middle of length of finished barrel. Rolled, and cooled in air.
Applied loads per square inch.	Elongation per inch.	Successive elongation per inch.	Permanent set.	Successive permanent set.	Remarks.
Pounds. 1,000 5,000 10,000 20,000 30.000 40.000 50.000	Inch. 0. .000100 . 000300	Inch. 0. .000100 .000200	Inch. 0. 0.	Inch. 0. 0.	Initial load.
	.000633	. 000333	1		
	. 001000	.000367			
	.001333	.000333			
	. 001667	.000334			
6o;000 70.000 80.000 86,000	.002000 . 002333	.000333 .000333	0.	0.	
	. 002667	. 000334			
	. 002867	.000200			Elastic limit.
87.000 88.000 90.000 95.000 100,000 105,000	. 02583S	. 002966			
	.026667	.000834			
	.029667	.003000			
	.036667	.007000			
	. 047667	.011000			
	.0700	.0223			
110,000 112,500	.0867	.0167			
					Tensile strength.
					
General summary.
Tensile strength per square inch of original section..........................pounds..	112,500
Elastic limit per square inch of original section................................do----- 86,000
Elongation per inch after rupture..............................................inch..	. 1867
Elongation per inch under strain at elastic limit................................do.....002867
Reduction in diameter at point of rupture........................................do........106
Position of rupture............................................................- l"-3 from neck
Character of broken surface.................................................... silky, cup-shaped
Elongation of inch sections.................................................... "•18, ".27*, ".11