The British 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 was that the lugs cleared each other immediately so full effort was applied to the extraction cam. The trigger had a mechanical interlock to prevent firing unless the bolt was fully locked. The nickel-steel action was large and strong and had a long bolt throw compared to other military service rifle bolt actions, since it had to be capable of handling the dimensionally large .276 Enfield cartridge variants, and the barrel was given a heavy profile. The Pattern 1913 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. It was a long and comparatively heavy rifle – the Lee-Enfield Mk III weighed empty – and the pronounced sight protector 'ears', the 'pot-belly' magazine and 'dog-leg' bolt handle gave it an ungainly air. The P13 is distinguished by unusual angled finger grooves on the fore end of the stock, which were not present on the later P14 and M1917. Some P'13s survived as target rifles in the UK, often having been "sporterized" (removal of wooden handguards and shortening of the stock). Very few were produced, and so very few survive. See also Pattern 1914 Enfield M1917 Enfield rifle Notes References External links THE UK PATTERN 1913, PATTERN 1914, and THE US MODEL OF 1917; A Short History of the “American Enfield” By Marc Gorelick Virginia Gun Collector’s Association Bolt-action rifles of the United Kingdom