I really like how Iain explains and develops a possible application for the opening sequence of Naihanchi Shodan (Tekki), and you can train it fairly well on a heavy bag. Some great strikes in there, and the combination flows nicely. Here's a video demonstrating solo training that combination on a heavy bag. Forgive the verbal explanation of the bunkai application (I made this before Iain suggested trying to demo the bunkai application with a partner instead of describing it--great suggestion!). However, I think most of you will be familiar with Iain's bunkai for this. If not, here is a video of his application:
I was using a palm up ridge hand, but I think the forearm strike that Iain demonstrates is much more devastating.
Here is my training it on a heavy bag: