Outlaw helm-motif drop rate?!

Ghettokid

Few last days i've been killing main boss in shark teeth grotto to get that outlaw helm motif. Still haven't got it even i have already got 6 outlaw leg motifs, 3 shoulder motifs, 2 staf morifs and 2 shield motifs. Can anyone say is helm motif more rare or something cause i want it very much?? I'm on ps4 European servers.