A post by Blue Forum user 'Luminous Wanderer':
Of general relevance are these links on 'limp-wristing', which is a cause of rifle malfunctions (especially the stuck cartridge casing problem, but others too):
http://firearmshistory.blogspot.co.uk/2012/08/what-is-limp-wristing.html
https://en.wikipedia.org/wiki/Limp_wristing
Note: Limp-wristing is not due to the strength of the gun user (though there is a relationship between the two), rather it is due to the method of gun-handling. In the context of semi-automatics, it could happen if Sheila was using the rifle without the stock, in other words, not primarily with the stock positioned in her shoulder.
However, semi-automatics don't tend to be susceptible to limp-wristing, for technical reasons - but it's possible in specific instances, and it's clear from Malcolm Fletcher's first witness statement that he did not bother to go to any lengths to diagnose the malfunctioning ballistically. It's something that would need to be studied further in relation to the specific model of weapon.