The Lee–Enfield bolt-action system was introduced in 1889 with the Lee–Metford and later Lee–Enfield rifles (the bolt system is named after the designer James Paris Lee and the barrel rifling after the Royal Small Arms Factory at the London Borough of Enfield), and is a "cock on closing" action in which the forward thrust of the bolt cocks the action. This enables a shooter to keep eyes on sights and target uninterrupted by cycling the bolt. The ability of the bolt between lugs and chamber to flex also keeps the shooter safer in case of catastrophic chamber over-pressure. The disadvantage of the rearward located bolt lugs is that a larger part of the receiver, between chamber and lugs, must be made stronger and heavier to resist stretching forces. Also, the bolt ahead of the lugs may flex on firing which, although a safety advantage, may eventually lead to increased head space. Repeated firing over time can lead to receiver "stretch" and excessive headspace, which if perceived as a problem can be remedied by changing the removable bolt head to a larger sized one (the Lee–Enfield bolt manufacture involved a mass production method where at final assembly the bolt body was fitted with one of three standard size bolt heads for correct headspace). In the years leading up to WWII, the Lee–Enfield bolt system was used in numerous commercial sporting and hunting rifles manufactured by such firms in the UK as BSA, LSA, and Parker–Hale, as well as by SAF Lithgow in Australia. Vast numbers of ex-military SMLE Mk III rifles were sporterised post-WWII to create cheap, effective hunting rifles, and the Lee–Enfield bolt system is used in the M10 and No 4 Mk IV rifles manufactured by Australian International Arms. Rifle Factory Ishapore of India manufactures a hunting and sporting rifle chambered in .315 which also employs the Lee-Enfield action.