I don't think Osprey packs are external frame. The reason it feels like the load moves around is because of the extreme angle of the frame moving the load away from your back. Osprey thinks this makes the pack cooler on the back. On me, the Aura 50 balanced the weight on my hips too well, causing very very sore pressure points and nearly tipping me backward at times on the trail. The load inside wasn't sitting well because the weight doesn't hug the back, and there wasn't adequate room inside for a bear can, either.

The frame itself is integrated into the pack, so it is still an internal frame - just not very comfortable for everyone. Some people find it fits fine, I needed something that kept the weight more balanced and less tip-prone. Granite Gear has a better, more adjustable frame and doesn't use aluminum.