a test was recently conducted which seemed to suggest that inaccuracy was not greatly influenced by the hole in the dart, and suggested that excess muzzle blast was actually the isue.
By "muzzle blast" i'm assuming you're talking about springers and air-powered blasters...
While firing overvolted Stryfes across an open basketball court I noticed that most of my (almost mint) N-Strike Elite darts would travel straight for about 30 ft. and then abruptly curve off in one direction, almost like a kicked or thrown ball that had some spin on it. Although the inside of the Stryfe barrel is rifled i'm skeptical that this leads to any spin of the dart and the initially straight trajectory tells me that whatever's going on happens to the dart in-flight.
While I have a limited number of Elites at the moment I plan on somehow sealing the holes in a few and testing them. Hell, I might even do a write-up. Unless someone has done it before and I haven't found that post.
EDIT: for completeness