While waiting for my raid team to start the Templar fight, I decided to screw around with some of my fusion rifles (FR) in my inventory. After shooting a couple of bursts with the Split Shifter, I switched to Perun's Fire. After shooting what I thought was my last shot and running empty, I was surprised to see my character reload the FR with 0 in the mag. I then was able to charge and fire a single shot (not a full burst, just a shot). This whole experience seems to suggest that the game counts the total amount of projectiles as ammo in the FR (not the actual amount of bursts left). As you may or may not know, switching weapons typically reduces the amount of ammo available for the new weapon by a percentage. This enables one to activate this "glitch" I mentioned earlier, since the game reduced the amount of FR ammo I had while switching. If the game counts FR ammo by the projectile and not by the burst, it would explain this anomaly that I found with the FR showing 0 but still being able to fire... Moral of this entire post is that FR ammo is counted by the projectiles left and not by the burst as the game would have you believe.