I don’t think the ammo is the problem, we can kill Ai soldiers and pick-up ammo, we can bash open wooden crates and get ammo.
What’s truly scarce during a match are gear items — which can only be replenished from ammo crates like: Field Syrette, Frag Grenade, and Flashbang for instance.
I agree @Chiefbigsnake having a C4 device would be great for missions that require destruction, but the FT doesn’t have to dump magazine after magazine into these objects. Similar to what I mentioned earlier about tactics and taking down targets with stealth knife attacks and avoiding alarm activation to conserve ammo.
For instance, the mission where 3 generators have to be destroyed — FT doesn’t have to waist ammo. The FT can use a single Frag Grenade or other explosive per generator (Hammerhead Grenade Launcher or D34-D) to start the fire or dump maybe a magazine of small arms shots to initiate the fire. Once a generator is on fire, your team can move to the next target and the generator will continue to burn until it detonates.
You don’t want to be near those massive explosions because they’ll draw hostile Ai and the attention of the Predator. I just do enough damage to cause each item to be on fire then book it out if the area. The Predator goes there as the explosions are going off and you’re already en route to the next objective.
The same holds true for destroying the servers, computers, or crates don’t waist ammo — use your knives with the heavy attack to destroy those items. By doing that you conserve ammo and make less noise for the Predator to detect your team by.
I very rarely am in dire need of ammo, health kits are always the thing of want for me. And circling back to OP and locating Ammo Crates, if a FT member spots an Ammo Crate, even when they don’t need ammo yet, it stays on your mini-map the entire match just like alarms, weapon crates and first-aid kits.