Hi.I got confused with let off here in WA

I check regs ,but can't find any information about let off .Way i remember around 8 years or more ago ,only 65% let off was legal and it used to be in regs ,now some one told me 80% let off it is ok WA .I am in market for new bow ,so i like to find out this true or not before i buy new bow .And when i check 2008 regs ,none been said about let off .

Thank you
Vadim