I've got the same problem of the nozle on g17 and hi-capa with Modify and 9ball hopup rubbers........
Mine was a problem related to the lube of the greengas I was used to usue.
After chance brand of gas all start to work good.
Now I use hopup rubber and nozle from Aip and all works great.
This is mine one, for the moment use abs slider but I mount a kit whit fixed barrel and light BBhousing
Here with 0,25 bb
the BB Housing is the one on the right
the inner of the slider compared with a stock marui