Bungie has the following in the TWID "Your power weapon will recharge ammo." I tried solo quick play to see if anything changed, with 1 heavy finder. The TWID makes it sound like the weapons get ammo out of the air similar to swords did a couple weeks ago. I launched into a solo quickplay with 63 heavy for my bitter end MG. I burned through that quickly using my heavy as a primary and it definitely didn't generate ammo out of nothing. I only got 2 heavy bricks for 63 ammo each, no heavy crates the entire activity. I then put triple heavy finder on and did another solo quickplay. There were more 63 heavy ammo bricks but would run out ammo between bricks. There was a heavy crate toward the end. My current build has 108 for the ammo stat. I know a higher number will make a difference but I don't consider this a surge. It's a little more than normal but needing triple heavy finder isn't worth it. The damage buff is great but it means nothing without ammo.