The "Wardering Zero" of the No5 MkI is once of the most repeated "factual" statements " in the milsurp collecting world. Most who see a No5 think to themseleves..."that's a Jungle carbine which has a wandering zero". The No 5 is just that: a No 5 MkI. The label "Jungle Carbine" was applied by commercial vendors in the US who wanted to hype up the batches of No5's than being declared surplus. The rifles did see use in Malayan and Indian conflicts but it was intended to be a replacement for the No4MkI rather than act as a "special forces" type of weapon. The No5 wasn't liked by the brass as they were keen to get their hands on an SLR that had been in development for sometime. There were reports from the field that the gun did have difficulty maintaining a predetermined zero but this was largely the result of the affect temperature and humidity had on the rifle's bedding. No5MkII versions alleviated this somewhat but there were other factors at play. The shape of the butt stock which caused the heel to rise ever so slightly on the shoulder when fired. The aforementioned lightening cuts in the rear of the receiver did cause some flexing. There was no real concerted attempt or interest to save the No5 as organizational momentum had already began to realize the adoption of the SLR. Any limitation or problem with the No5 could only be beneficial to those pushing for the adoption of an all new weapons platform not based on the Lee Enfield.
I've owned and fired a number of No5's over the years and they are fine reifles with cast or jacketed rounds. Any accuracy problems that arose were due to the condition of the bore, loose actions or were technique related. I personally dislike the over sized aperture on the standard No5 sight and find it difficult to maintain a repeatable sight picture. The aperture on the leaf is better but I prefer to use a Parker Hale 5C with interchangeable aperture. Once set to my preference my No5's have always achieved very good accuracy comparable with the No4 out as far as 300 yards. I shoot prone with a sling from a consistent position. IMO bench fired No5's with standard sights produced acceptable accuracy but the flinch inducing recoil and vague open sight picture don't induce confidence in the shooter. When it comes to accuracy in No5's you have to have a clean bore, tight action and stock, a good sight picture and a repeatable shooting position.