What is a walker?

[typhoon_driver]

I'd need to see plans to make sense of it

I wouldn't have an issue with a 25% increase in weight for a shuffler/hopper/pure non rotary. But for a 100% increase in weight I want to see a full on walker. Not something that just skirts around the rules

Bear in mind that in a feather you are getting an additional 13.6kg. That is a huge weight increase and a good weight to allow you to build a rugged chassis and mechanism. Then you have the rest for a weapon!