Both. The rate of fire was much slower which i don't have a problem with as full auto is rarely used, but it was the cycling and gas efficiency that drastically declined. One of the MWS' defining traits is how snappy it is compared to GHK/WE/VFC and it just killed it dead. it's fun to throw some black gas in it and empty a couple of mags in the summer, but as a usable system, it's not for me. A Slightly stiffer spring would probably be the best all around option as the forward spring pressure seats the nozzle into the chamber as it speeds up the return cycle