The new-in-wrap rifles frequently do not have proper forend fit, either from wood seasoning over 50+ years, or - more likely - the forends were never fitted correctly at the factory. Often the handguards are also a little on the "fat" side in the barrel channel, and need some attention. The front trigger guard screw bushing is usually unfitted/untrimmed as well - leading to poor receiver contact at the bedding points. I guess the factory intended that the end-user - the unit armourer - would do the final set up of each new rifle.
Finally, the bore of a NIW is new and often the rifle's performance improves over the first 200 rounds or so.
A lot of NIW owners express disappointment over the poor shooting performance of their mint rifles, and are dismayed that a tatty old No4 at 1/4 the price they paid for their beauty can often out-shoot them!