An Apex Legends player on TikTok showed off a rather interesting exploit that allows Rampart to have infinite ammo with Sheila, even when detached. Currently, Rampart can activate Shiela and run around with her minigun. The only difference is that you have one magazine of 173 rounds. If you use them all, you're out unless you plant the weapon. If you plant the weapon as normal, then you have infinite ammo, but you won't be able to pick it up again. That is until you unlock the cooldown again.
That's where this TikTok comes into handy.
TikToker rossbobsquirrel shows off a rather easy way to do it. Once you are out of ammo, hit the melee button, and you'll notice that your ammo starts to go back up. The only caveat is it goes up rather slowly. So yes, you could potentially have unlimited ammo even when mobile, but at the rate it returns, you'll have only around 30 rounds between fights. This might not be worth it in the long run.
Things keep adding up for Rampart as Apex Legends might be seeing a new meta. Her pick rate has skyrocketed since her buffs, and she even has her own exploit. Respawn does a pretty good job at balancing and is reluctant to change things in hopes to keep things fair. But this might change with Rampart. With her drastic rise, Respawn may tune things back, slowly down her ascent or they may leave her alone. We'll just have to wait and see.