No4 Bolt head question

[Alan de Enfield]

Anyone know if it is also 16-20 degrees for the No.1MkIII bolt head?

The 1912 and 1931 "Instructions to Armourers" do not appear to quote an acceptable displacement of the bolt head in relation to the bolt - except for -


4. Action:—Bolt and bolt-head.

(i) Test the distance of the bolt from the end of the chamber with gauges .064-inch No. 1 and .074-inch No. 1; the bolt should close over the .064, but not over the .074; when using the latter gauge, light thumb-pressure only should be applied to the knob. Also test to see that the wing of the bolt-head does not lift off the rib of the body.

(ii) Examine the bolt for fracture and damage, especially at the cocking cam and recoil shoulders. Test the striker for free movement and fit in the cocking-piece: gauge the length and radius of the striker point; examine the bents and condition of the cam stud of the cocking-piece.

(iii) Test the fit of the bolt-head in the bolt, and examine the face for erosion; when erosion is excessive or the rib turns beyond the rib of the bolt freely, fit a longer bolt-head and adjust to the 064 gauge as necessary.

(iv) Examine the extractor at the hook and for fit on the screw, and test to see that the screw is secure. Weigh the spring from the hook with the trigger tester - not less than 6 lb. and not more than 9 lb. should be required to move it.

Note.—The bolts of rifles in use should be completely stripped at each annual examination and lubricated lightly with G.S. oil.


Are they talking about the overturn ?