77
RIFLE-BARREL STEEL, .30 CALIBER.
No. 7398.
Marks, M 3 C.
Sectional area, .25 square inch. Gauged length, 1".
From butt of finished Barrel.
Eolled, and cooled in the air.
Applied loads per square inch.	Elongation per inch.	Successive elongation per inch.	Permanent set.	Successive permanent set.	Remarks.
Pounds. 1,000 5,000	Inch. 0. .0001	Inch. 0. .0001	Inch. 0.	Inch. 0.	Initial load.
10,000	.0003	.0002			
20,000	.0006	.0003			
30,000	.0009	.0003			
40,000	.0012	.0003			
50,000	.0016	. 0004-			
60,000	.0020	.0004			
70.000	.0025 .	.0005			
76,000	.0028	.0003			Elastic limit.
77,000	.0080	. 0052			
78,000	.0130	.0050			
79.000	.0155	.0025			
80,000	.0167	.0012			
82,000	.0187	.0020			
84,000	.0205	.0018			
88,000	.03	.01			
92,000	.04	.01			
100, 000	.05	.01			
108,000	.08	.03		*	
113,200					Tensile strength.
					
General summary.
Tensile strength per square inch of original section............................pounds.. 113 200
Elastic limit per square inch of original section...............................do.	76000 ׳
Elongation per inch after rupture...............................................inch.	’. 21
Elongation per inch under strain at elastic limit...............................' .do.!!	. 0028
־׳Character of broken surface.......................... fine granular 40 per cent, silky 60 per cent