Speaker terminal Loose

Millercarbon.   You are correct about sacrificing spring action and sonics.  Having a pure copper base is always better than less conductive brass.  But copper is soft and difficult to machine.  That is why you still see most "high end" speaker connections and RCAs made with some kind of plated brass.
The only banana plug I know of that is pure copper are the Furez connectors.   They are soft but they have a plastic insert that helps with holding them to shape.  They grip good but do need an occasional expanding when they are plugged in and out a number of times.  I have not noticed them losing their grip if they remain plugged in.
I do like spades.......just wish they would fit on all of my amps.

erik_squires   I try to open one Furutech end of the banana and broke one of the piece ! I think I would use BFA gold over brass crimping banana. Thank's.  I think Furutech are fragile with some  of their parts.

I found on my Furutech expanding bananas, if you remove the screw expansion pin, you can take a small file, and file down the area on the plug where the pin threads in, you can get more tightness due to the pin going in a bit further in, making for greater expansion on the banana plug. 

Works for me.

Dan

@Dan

You are proving my point. You don't need to with WBTs.

;-)

Whatever you buy, something other than Furutech is my suggestion.

Soldered-on low mass BFA Style Banana Plugs for me, every time! I've been using them for more than 20 years and never had an issue. Never had one loosen. No problems, ever. I started with Nordost Z-plugs, but later changed to less expensive options that were functionally the same.