When I worked with Bill Duke on redesigning their stop loss,the first thing I had the do was remove the delay pin completely.Number 2--was to remove the chain from the jaw end of the trap, and move it to the spring end of the trap.When the chain is attached to the jaw end,muskrats have to much free chain and are able to pull right up onto the house or feedbed.
I have never gone along with attaching the chain to the jaw end-----I have never had a problem holding any animal caught in a #1 stoploss.They key is a good strong spring.I have held countless numbers of coon over 30 pounds,and my largest beaver caught in one, was 53 pounds.
Tom