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RECOIL MECHANISM---15-POUNDER GUN NO. 12.
Simultaneous readings taken are gauged lengths A1 and B. Gauged length A1 established from fixed block near rear end of recoil cylinder to rear end of lug of sleeve.
Applied loads.	Gauge readings.		Remarks.
	On AL	On B.	
Pounds. 1.000 10,000 20,000 40.000 60.000 70.000 i, 000 72.000 1,000	Inch. 0. .0061 . 0141 .0288 .0420 .0701 . 0228 .0879 .0388	Inch. 0. .0031 . 0066 .0138 .0205 .0232 0. .0241 0.	Micrometers reset at zero.
Recoil Mechanism of Driggs-Seabury Fifteen-Pounder Gun
No. 12.
SUPPLEMENTARY TEST WITH REENFORCED CAST-STEEL SLEEVE AND REENFORCED BRONZE OSCILLATING SLIDE.
The sleeve was reenforced by additional metal, gusset shaped, at the root of the lug•. The oscillating slide had a ribbed steel cap across the top and a steel lug brace on the bottom side.
Gauged lengths designated by the letters before used in the tests with this gun refer to the same places on the gun. The new gauged length Q was established to show the movement of the slide within itself, and was defined at one extremity on the front end of the lug, and at the other end on a strap which was bolted to the sides of the slide at the rear end.
The tests were made in the order in which the details are reported. Following the methods of previous tests, loads were applied in successive increments up to 60,000 pounds tension, and then observing the resilience as the loads were successively reduced.
In the present tests, observations on gauged length A showed an extension of ".0090, against ".0340 in the earlier test, indicating apparently a greater degree of rigidity in the reenforced steel sleeve over the ordinary bronze sleeve.
On gauged length C a greater movement was observed than in the previous test, a part of _ which excess was attributed to the greater strains developed in the piston rod and the remainder to the slide itself. Ihe net movement of the piston rod, gauged length B, was found to be ".0210 to ".0211, against ".0179 of the previous test. Special treatment in the earlier test had been the means of obtaining a higher extension. This comparison, however, refers to the ordinary state of the mechanism.
In recoil position, during the present test, the total extension of the piston was ".0197 to ".0201.
On a gauged length from corner to corner of the rear lower end of the slide, a movement of ".123 and ".115 was found when the gun was in firing and recoil positions, respectively. This movement took place in an outward direction.