page_title: M1917 Enfield
section_title: Design details
hierarchical_section_title: M1917 Enfield / Design details
caption_attribution_description: English: P 17 Bolt
context_page_description: The M1917 Enfield, the "American Enfield", formally named "United States Rifle, cal .30, Model of 1917" is an American modification and production of the .303-inch Pattern 1914 Enfield rifle developed and manufactured during the period 1917–1918. Numerically, it was the main rifle used by the American Expeditionary Forces in Europe during World War I. The Danish Sirius Dog Sled Patrol on Greenland still use the M1917, which performs reliably in Arctic conditions, as their service weapon.
context_section_description: Like the M1903 Springfield, the M1917 actually used the basic Mauser M98 bolt action design coupled with a few modifications. Due to the original P13 action being designed for a high-powered .276 Enfield round with a larger diameter case than the .30-06 Springfield, the magazine capacity for the smaller diameter .30-06 Springfield was six rounds, although stripper clips held only five cartridges.
  Both P14 and M1917 rifles are noted for several design features. The rifle was designed with an iron sight line consisting of rear receiver aperture battle sight calibrated for 400 yd (366 m) with an additional ladder aperture sight that could be flipped up and was calibrated for 200–900 yd (183–823 m) in 100 yd (91 m) increments and 900–1,600 yd (823–1,463 m) in 50 yd (46 m) increments. The ladder aperture sight moves vertically on a slide, and hence was not able to correct for wind drift. The rear sight element was protected by sturdy "ears" and proved to be faster and more accurate than the typical mid-barrel sight offered by Mauser, Enfield or the Buffington battle sight of the M1903 Springfield. Future American rifles, such as the M1903A3 Springfield, M1 Garand and M1 carbine, would all use similar rear sights. The front sighting element consisted of a wing-protected front post, and was adjusted laterally and locked into position during assembly at the arsenal. The M1917 rear sight element was situated on an elongated receiver bridge, which added weight to the action, as well as lengthening the bolt. The M1917 has a 31.76 in (806.7 mm) sight radius. The battle sight radius is slightly shorter at 31.69 in (804.9 mm).
  The M1917 action weighs 58 oz (1,644 g) versus 45 oz (1,276 g) for the M1903 Springfield.
  The rifle maintains the British cock-on-closing feature, in which the bolt's mainspring is loaded and the rifle cocked as part of the return stroke of the bolt, which aided rapid fire, especially as the action heated up. Most bolt action designs after the Mauser 98 cocked as part of the opening stroke. The rifle has a characteristic "belly" due to a deeper magazine, allowing the rifle to hold six rounds of the US .30-06 cartridge in the magazine, and one in the chamber. The M1917 Enfield like the Mauser Gewehr 98 had no magazine cut-off mechanism, which when engaged permits the feeding and extraction of single cartridges only while keeping the cartridges in the magazine in reserve. In a manufacturing change from the Mauser 98 and the derivative Springfield, the bolt is not equipped with a third 'safety' lug. Instead, as on the earlier Model 1895 (Chilean) Mauser, the bolt handle recesses into a notch in the receiver, which serves as an emergency locking lug in the event of failure of the frontal locking lugs. This change saved machine time needed on the rifle bolt, cutting costs and improving production rates, and this alteration has since been adopted by many commercial bolt-action rifle designs for the same reasons.
  The unusual 'dog-leg' shaped bolt handle is low profile and places the bolt knob just rearwards of the trigger close to the firer's hand, facilitating rapid cycling and fire. Like the Lee–Enfield, P13 and P14, the safety falls under the firer's thumb and can be operated silently.
  The M1917 Enfield bolt locking lugs had a 4 degree helical angle with matching angles on the receiver lug seats (the technical term is interrupted  threading). This means that final head space is not achieved until the bolt handle is turned down all the way. The design probably used helical locking lugs to allow for chambering imperfect or dirty ammunition and that the closing cam action is distributed over the entire mating faces of both bolt and receiver lugs. This is one reason the bolt closure feels smooth. The angled lugs had no tendency to unwind with chamber pressure since the "angle of repose" of smooth, lubricated steel surfaces is approximately 8 degrees. One advantage was that when the bolt handle was turned up the lugs cleared each other immediately so full effort was applied to the extraction cam. The trigger had a mechan
caption: M1917 Mauser M98 type bolt
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