The shock cord seemed a little short for me, they usually are.
Rather than cut a new piece of elastic, I simply tied on another scrap piece.
A square knot was tied and with about 3/8" of loose tail on either side.
Don't pull it tight yet!
If you left the knot a little loose it's easy to slide the wire through.
Close up the swivel and it's ready to go!
All knots should be periodically checked before flight to be sure they haven't loosened up.
I don't like using glue on a elastic to "set" the knot. White glue dries hard and could wear down the elastic.
The end is tied off on the nose cone shoulder lug.
TIP: On a nose cone like this, there is an open slot below the tie off loop.
If the elastic were left long it might get caught between the shoulder and body tube.
Leave the end a little long and tie an overhand knot near the end.
With tweezers, force the knotted end into the slot.
The knot will keep the long end inside the nose cone shoulder.
That wrap of masking tape will be replaced.
It still has some red paint dust on it from some wet sanding.
The nose cone was just a little loose in the BT-50 tube and needed 1/2 wrap of tape around the shoulder.