With magnets being 5-10% more powerful when attracting rather than repelling - I imagine some kind of a design with the piston head being a magnet with an o ring groove machined into it, and the plug at the business end of the cylinder being another magnet with a TP drilled through it.
Perhaps a hybrid system would be more achievable? Using a conventional coil or gas spring - with the magnets giving a bit of extra power at the end of the stroke, and more importantly, acting as an anti-bounce system?
Yes, I'm sure that would work. And breaking the magnets apart would be done with a quick "slap" on top of the barrel. So a stiffly sprung chisel point barrel detent would be required - like on a Theoben rammer.
I believe Norm could be in for a Nobel Cheese Prize for this - if it works out.
(although he might have to wait until infinitely more powerful magnets are developed)