Stainless steel is extremely hard to solder properly. You can aneal the non threaded end by heating to red hot. Try to not heat the threaded end. Flatten the end and drill a hole only as large as yor leader needs, loop your wire thru a ferrel made of small alum. or brass tube about 1/2 inch long, thru the hole, back thru the ferrel and crimp. Give it a good pull test. 30 lb test is fine; I understand it is tested by dropping a 30 lb weight one foot!

good luck.