Had similar problems with my wa svi 6" ltd; poor castings, uneven paintwork, loose slide & frame fit, leaky mag, inconsistent shots, etc. etc. etc.
After spending hours smoothing and tuning it I pretty much gave up when I realised it wasn't going to get any better without further investment.
I now use it to prop up a table leg and as a reminder never to never again buy an overexpensive wa POS.