Gun Runner Achievement in Halo Infinite
Take down all three Banished AA guns in under 20 minutes.
Partway through the campaign you and the pilot will be shot down by AA-guns, once you crash three markers will come up in which three of the Bannished AA-guns will need to be destroyed. Once you enter the first gun , a cutscene will play on but afterwards the weapon Ai will tell you your all set and a power cell (glowing yellow crystal) will appear, once you shoot it, the AA gun begins to self destruct, *only after it expodes the timer starts*, so you have 20mins to get to the last two , for me I attacked afew enemies on the way but didn’t waste all that time attacking them all. Once you enter the final gun and destroy it, the achievement should pop if done in the timely manner.
Note: Halo infinite achievements on my end at least are delayed for a minute or 2 , so don’t worry if it doesn’t pop right away, in fact close out the game if nothing pops within the next 5mins, I did this for some other achievements and it worked.