Strangely, that reminds me of the last Robert Asprin book I read, 'For King and Country', about an SAS operative who goes back in time to the Arthurian period to stop an IRA terrorist from destroying England in its infancy. It was nothing like the Myth books, but still rather decent.
As for now, I'm reading "The Bren Gun Saga, revised and expanded edition", by Thomas B. Dugelby. Like pretty much everything put out by Collector Grade Publications, it's a definitive look at the evolution of the weapon in question. Of course, if you're not an absolute hoplophile like myself, it may be too technical and/or boring for your taste. But at least someone out there writes gun-related reference books that go beyond 'It shootz bulletz at teh badguyz!!!". It's really too bad that Dugelby's dead.