Swapping Internals of Diana 350 N Tec & AR8 N Tec w/350 Mag

[Yuganz]

So the gas piston of weihrauch HW90 can be serviced at home. I have not owned any of the 350 variants only 34/36/38/45 springer. Is it possible to do same for 350 N Tec or AR8 ? If not when the gas runs out can one replace it with piston and conventional spring of the 350 classic ?

Thanks.

Yuv.