Paragraph
General   ......................................................................................................		54
To disassemble the breech mechanism   ........................................................		55
To assemble the breech mechanism   ............................................................		56
To disassemble the breech actuating mechanism   ...........................................		57
To assemble the breech actuating mechanism   ..............................................		58

54. GENERAL.

a. Wear, breakage, cleaning, and inspection, make necessary the occasional disassembly of various parts of the gun and mount. This work comes under two headings, that which may be performed by the battery personnel with the equipment furnished and that which must be performed by trained ordnance personnel.

b. The battery personnel may, in general, do such dismounting as is required for battery use. Such work should be done in the manner prescribed herein. Any difficulty which cannot be overcome by the prescribed method must be brought to the attention of ordnance personnel.

c. The battery personnel will not attempt to disassemble any part of the recoil mechanism not authorized in this manual, nor do any filing on the sights or gun parts; and only by order of the battery commander on any mount part.

d. The use of wrenches that do not fit snugly on the parts should be avoided. They will not only fail to tighten the part properly but will damage the corners of the nuts and bolt heads. There is also danger of spreading the wrenches and rendering them useless.

e. Before attempting the assembly of the larger mechanisms, the assembly of the subassemblies should be completed. In all assembly operations, the bearings, sliding surfaces, threads, etc., should be cleaned and lubricated.

55. TO DISASSEMBLE THE BREECH MECHANISM.

a. Set the gun at a 0-degree elevation and close the breech. Remove the locking pin (fig. 13) and remove the breech operating crank (fig. 62).

Figure 62 — Removing Breech Operating Crank

b. Disengage the "SEMIAUTOMATIC-HAND" ("SEMIAUTOMATIK-HAND") catch from the breech actuating mechanism (fig. 52). Then remove the breech actuating mechanism as a unit (fig. 63).

Figure 63 — Removing Breech Actuating Mechanism

c. Rotate the extractor actuating lever and remove it from the breech ring (fig. 64).

Figure 64 — Removing Extractor Actuating Lever

d. Open the breech sufficiently and remove the breechblock actuating lever (fig. 65).

Figure 65 — Removing Breechblock Actuating Lever

e. With the breechblock open 2 inches, press the heels of the extractors into the recesses of the breechblock.

f. Open breech sufficiently and remove the extractor (fig. 66).

Figure 66 — Removing Extractor

g. Rotate the cocking lever counterclockwise until the handle is toward the muzzle. The lever may now be lifted out (fig. 67).

Figure 67 — Removing Cocking Lever

h. Remove the breechblock.

i. Fire the percussion mechanism by depressing the operating rod and rotating the sear operating lever (fig. 68).

Figure 68 — Breech Mechanism — Exploded View

j. Press in and rotate the firing spring retainer through 90 degrees. Remove the retainer and firing spring (fig. 68).

k. Rotate the cocking arm and remove the firing pin holder to the rear (fig. 68).

l. Lift out the cocking arm.

m. Depress the operating rod and remove the safety stop lever (fig. 68). The operating rod with spring may now be removed (fig. 68).

n. Press the sear down and remove the sear operating lever (fig. 68). The sear and spring may now be removed (fig. 68).

56. TO ASSEMBLE THE BREECH MECHANISM.

a. To assemble the breech mechanism, perform the steps necessary to disassemble the breech mechanism in the reverse order.

57. TO DISASSEMBLE THE BREECH ACTUATING MECHANISM.

a. With the breechblock removed, replace the breech actuating mechanism as a unit in the breech ring, with the breech mechanism actuating lever and breech operating crank assembled.

b. Engage the "SEMIAUTOMATIC-HAND" ("SEMIAUTOMATIK-HAND") catch to the breech actuating mechanism.

c. Remove the locking pin and locking collar from the actuating shaft (fig. 69).

Figure 69 — Breech Actuating Mechanism — Exploded View

d. Rotate the breech mechanism actuating lever slightly towards the open position and remove the actuating mechanism upper housing (fig. 69). Allow the lever to rotate beyond the closed position until all spring pressure is lost. Remove the upper spring and top spring cover (fig. 69).

e. With the actuating mechanism in closed position, set the actuating lever and rotate the mechanism beyond the closed position and hold while the intermediate plate (fig. 69) is lifted up and removed; then gently ease the lever beyond the open position until all spring pressure is released. Remove the lower spring and the actuating mechanism lower housing.

f. Remove the spring lock (fig. 69).

58. TO ASSEMBLE THE BREECH ACTUATING MECHANISM.

a. To assemble the breech actuating mechanism, perform the steps necessary to disassemble the breech actuating mechanism in the reverse order.