kwa g23f multiple rounds issue

[tewilk]

New to airsoft so if I'm over looking something... sorry in advance. My issue is that my "new" kwa glock 23f is shooting 2 and sometimes 3 rounds in one shot in semi-automatic mode which I don't understand. Everything has been oiled that rubber or is a moving part. Using propane if that matters... only thing I can think of is that the return spring is slightly too weak. If you play with the mag, all it takes is a slight forward pressure and the BBs pour right out (so a slow return cycle could allow for multiple loads... the way I see it anyhow). I used the full auto mode one time so I can tell much from that mode as it pertains to BBs coming out per cycle. Also the problem typically occurs mid to end of the magazine. I can fire 18/20 rounds out 23 most of the time. Most of my testing has been in doors where the temps has been 72 to 76.

tia!