MARK 6 MOD. 1 PISTOL CALIBRATION

7. While the procedure for calibration of Mark 6 pistol is generally applicable to the Mark 6 Mod. 1 pistol, additional instructions are necessary due to the leak proof feature and other slight modifications of this pistol. The following instructions are given for the Mark 6 Mod. 1:

(a) The index pointer plunger in the Mark 6 Mod. 1 pistol projects through the top of the pointer lug and it is staked to hold it in place. Therefore, the instructions or comments pertaining to the plunger noted in paragraph 6 (e), 6 (j), and 6 (k) do not apply.

(b) The index pointer and index pointer carrier are locked together with set screws and external-internal type lock washers are fitted on round head brass screws. This method of securing the parts eliminates locking by solder and it is used on pistols of recent ma-nufacture. In such instances it will be obvious that the instructions and comments noted in paragraph 6 (c), 6 (d), 6 (f), and 6 (g) are appropriately changed to fit the circum-stances. Loosen the set screw in the deep firing mechanism body but do not unscrew the mechanism.

(c) Whenever it is necessary to recalibrate a Mark 6 Mod. 1 pistol on which the index pointer screws and deep firing mechanism are locked in place with solder, the complete depth setting sleeve-dial plate sub-assembly should be removed from the pistol after the solder has been melted and the deep firing mechanism unscrewed.

(d) Take out, the two screws that secure the index pointer to the index pointer carrier and separate these pieces. It will pro-bably be necessary to use heat to melt the solder that holds these parts together. Clean off all the solder remaining on the parts removed from the pistol.

(e) Install a new gasket between the neck of the depth setting sleeve and the dial plate (as shown in the illustration).

(f) Clean threads of deep firing mechanism body and apply a new light coating of joint and thread compound to the threads, shank, and underside of flange of the body.

(g) Unsing the assembled fixture (BuOrd Dr. No. 389098) make up the sub-assembly with the chisel marks on index pointer and index pointer carrier in alignment. Locate the hole in the dial plate in the line with, and 180 degrees from the "V" on index pointer.

(h) Place a new dial plate gasket in position on the pistol carry-ing flange.

(i) Now test the sub-assembly as noted in paragraph 16 and re-place it in the pistol. This is done by lining up the "V" on index pointer with 30-foot mark on carrying flange and then turning the subassembly clockwise two complete turns. Screw on the dial plate lock ring and seat it firmly with a drift.

DEPTH SETTING ASSEMBLY FIXTURE

(j) The pistol will now be in the same condition as it was before disassembly except that the parts formerly locked together with solder will now be free.

(k) Loosen the two index pointer screws. Hold the index pointer at the 100-foot mark and, by means of the two screws, rotate the depth-setting sleeve a small amount clock-wise if the firing pressure was less than 40 psi or counterclockwise if the firing pressure was greater than 49 psi.

(l) Tighten the index pointer screws and test the pistol to determine the new firing pres-sure.

(m) Repeat the foregoing procedure until the firing pressure is as close to 44.5 pounds as possible and is within the specified limits (40 to 49 psi).

(n) Tighten the index pointer screws and turn the index pointer to SAFE. Test the pistol with the index pointer at the 30-foot mark as a final check on the calibration. The pres-sure required to fire the pistol at the 30-foot mark is 10 to 15 psi. No adjustment is pro-vided for calibrating the pistol at the 30-foot setting.

(o) Cock the pistol and leave it cocked. Lock the inlet valve body and the index pointer screws to the index pointer with spots of solder.