I use Dunlops on most instruments and Warwicks on my Warwick.
The ball and groove system seems to lock a lot tighter and more securely than Schaller's design and the Dunlops have one massive improvement in the design. A circlip!
They are a little harder to fit but the benefit is that you dont have to constantly check that a nut is tight enough to hold the strap.
Exactly.
I've been using them for over thirty years, with some installs that old. I've had basses with Schallers and the simplicity of the Dunlops vs. the horseshoe mechanism is what really impressed me. Push a button and "click", it locks into place, push it again to remove it.
I am curious as to what sort of difficulty some folks are having doing this. Are you trying to insert it without pushing the button in?
