From the British War Office (30th September, 1931)
INSTRUCTIONS FOR ARMOURERS
Drawing Nos. S.A.I.D. 2058; 2059; 2267; 2268; 2269.
7. To fit new bolt-head to Rifles No. l.—(Spare part bolt- heads, marked “S” on the top, are longer at the front.) Assemble the bolt-head to the bolt, insert it in the body, and test with .064-inch No. 1 gauge; should the bolt not close over the gauge, remove the bolt-head from the bolt, and having placed a piece of emery cloth (No. F) on a flat surface, rub the face of the bolt-head on the emery cloth, maintaining a circular motion in order to preserve a flat surface, until sufficient metal has been removed to enable the assembled bolt to close over the gauge. The bolt should not close over the .074-inch No. 1 gauge. Care should be taken to keep the-face of the bolt-head flat and square. After fitting and adjusting, the top front edge of the face of the bolt-head is to be rounded to a radius not exceeding .02-inch.
Note.—When it is found that the bolts of several rifles turn over the 074-inch No. 1 gauge, the bolt-heads should be ex- changed among such rifles, as, owing to the varying lengths of bodies and bolts, bolt-heads which are too short in one rifle may be serviceable in another. Bolt-heads that have been replaced in rifles by longer ones, should be kept by the armourer and used whenever possible in rifles requiring the bolt-head replaced, so as to avoid unnecessary use of new spare part bolt-heads. Part-worn bolt-heads held as required by armourers in accordance with the foregoing need not be accounted for as part of the annual allowance of new spare parts.Section 6.—Description and Use of Armourers’ Gauges
and certain Tools
GaugesGauges, armourers’, .064-inch No 1 and .074-inch No. 1 for rifles No.1.-These gauges are used also for .303-inch machine- guns, with the exception of the .074, which is not used for Vickers guns.
The gauges are for testing the distance of the face of the breech bolt from the end of the chamber, or, in other words, the cartridge head space. The diameter of the rim conforms approximately to that of a maximum cartridge. The portion which enters the chamber is merely a guide—not a gauging feature.
When closing the bolt on the gauge, the trigger should be held back to prevent cocking and snapping, which is liable to cause the rim of the gauge to be broken off. Care should also be taken to avoid drawing the gauge back on to, and so damaging, the ejector. In no circumstances must these gauges be used for No. 3 rifles, as the rim is slightly too large in diameter for the recess in the face of the bolt of those rifles, and, consequently, in addition to giving a false gauging result, will cause damage to the wall of the recess or the projecting horns on the left recoil lug of the bolt.
Gauges, armourers’, .064-inch No.2 and .074-inch No.2 for rifles No 3.—These gauges are special to No. 3 rifles and must be used only for those rifles. They differ from the No. 1 gauges in that the diameter of the rim is smaller and the portion which enters the chamber is longer, the front end being tapered off.
The instructions given for the use of the No. 1 gauges are applicable also to the No. 2 gauges.
The No. 2 gauges are obtainable on loan from store when required.