Russell Turner was a Pennsylvania gunsmith and inventor who developed this semiautomatic conversion of an SMLE bolt action rifle circa 1940. It was intended for trial and potential sale to the Canadian military, as it would allow them to retrofit existing rifles into semiautomatic configuration and still use existing supplies of .303 British ammunition. Rather than try to devise a reliable system to rotate the original Enfield bolt, Turner replaced the bolt entirely, using instead a side-tilting design much like what he used in his M1 Carbine trials rifle for the US military. This was coupled with a long stroke gas piston and a hammer firing trigger mechanism.
Reportedly the rifle was tested by Canadian authorities, and performed quite well, with the adjustable gas system allowing it to function reliably even in temperatures of 25 below zero (where the Garand, tested alongside, experienced problems). However, Turner’s rifle was deemed to complex for military adoption.
That decision against the rifle was probably the right one for Canada, although Turner’s conversion is one of the better semi auto bolt acton conversions I have handled. It was remarkably non-awkward – that may not sound like much to crow about, but it sets a pretty high standard for this type of rifle.