>>5337503All bullet tip darts are 7.2cm. The old suction cups, whistlers, and taggers are longer and have a bulky head. Most off brands have a similar bulky head. Some Buzzbee darts are longer, some X-Shot/Zuru darts are shorter.
The most ideal dart I've come across for magazines are the X-Shot/Zuru Bug Attack darts. They don't have the rubber tip most Nerf Darts have these days, they have a foam tip. This means two things, they lack that compression hole which reduces the impact but also greatly reduces accuracy, but the foam tips drag less when inside the magazine allowing for faster feeding. 30 for $5 also beats out Nerf's prices.