I was in the manufacturing business for 45 years, the last 32 years as a manufacturer of products sold worldwide through reps, and distributors. I went from design engineer to president of the company. I have 5 patents on products we sold, and have been sued for one unpatented design. We won on a directed verdict before we even put on a defense. If I saw a good design element, and if I could use it, I did. Was that a copy? Maybe so, but I am not ashamed of copying some design aspects. That is the road to better products, use the good ideas. No one seems to be complaining about loading presses and dies looking the same.
Effective patents are ridiculously expensive to obtain and to defend, and if someone violates all but one of your claims, he is not violating the patent. Mechanical patents typically have 10 to 100 claims. Small companies, in a limited market like reloading, may not be able to afford to patent. Think $10,000 to $50,000, can you sell enough to pay for the patent before you start making money?
And why "copy" another guys' product? That's easy, there is a market segment that you are not getting, it is in your business area and capability of manufacturing, so it will add to your bottom line. So you check patent status, define what the product features are, and tell your engineering people to design it. This is not significantly cheaper that starting from scratch on a design, you still have to do all the work, including prototype and final product testing, as well as writing tech manuals, and advertising for product release.
So let's not confuse everyone with this Big guy, Little guy stuff. The Big Guy was once a little guy. They all have to go through the trials and tribulations of the markets they desire to serve, and they have to play buy the rules of that market. Typically people who are not in Product design and manufacturing business have no idea of the rules. This is capitalism in action, good ideas prevail, if they sell, the product prevails, if not, the company fails.
Note that the copy was of a Henderson, great outrage developed. Would that had happened if the copy was of Giraud, Lyman, Midway, Wilson, little Crow, or other manual trimmers? I suspect Hornady went after the high end to add to their sales volume. For those who swear off Hornady for "copying" that's OK, just buy your stuff from another company that you have determined has not "copied" anything. That alone is a tougher job than you can imagine.
Summary: Copying is not BAD. All designs include some copying. Patents are expensive and not foolproof.
Design the best product you can, and if it sells. good for you.