How do I do Axton the Commando's speed glitch?

Axton speed glitch is done from an off-host player, this is because there is something built into the game to make connections to hosts more efficient. Using the skill Expertise a player can stack their ADS movement by throwing their gun while looking down the sights. This can be done how ever many times you wish.

This exploit can only done off-host because connecting to another player changes character saving from the Single-Player method of saving all the character data at once (including whether the player is looking down sights.) to the Multi-Player method of sending status effect and some player data to the host. (Including speed, but not whether their looking down sights. That's why it stacks when they ADS again.)