Did you buy the gun new? Are you sure that both mags are completely the same? I would take dial calipers and measure both mags in the same spots. Their has to be a reason one fits better than the other.
The WE is a popular gun, you should be able to find somebody on here that uses the same mags that you could meet up at SOGO. I can always bring my dial calipers next time I drive down if you don't have some available.