If you want plenty of detail about the use of your rifle in service look out for a copy of the UK government's 1951 sniping pamphlet. It is called a pamphlet but it's a small book! If you want a good general grounding on sniping over the last century, with plenty on the 4T included, then Skennerton's 'The British
Sniper' is very good, though the photographs seem a little grainy by modern standards....but then it did appear nearly forty years ago, & is a must if you're seriously interested. The other text is much more recent & was written by one of our very own forummers, & that's Steve H's book on a century of British army sniping. Forget the exact title but someone will no doubt chip in with it shortly.......lots of very high quality close up photo's in this one, too. And of course Peter L's books; on the rifle & on the No32 scope - I see the rifle book has already been mentioned.