Use caution when using custom replacement crossbow strings.
Some years ago I had an accident with a Horton Vision that let go (discharged) while I was loading a bolt, resulting in the loss of three fingertips. The bow was cocked, on safe and in a sled; I never touched bow or the trigger, just the bolt as I slid it back. As soon as the bolt touched the string it discharged.
For a long time I could not understand what happened, but in hindsight, I had just had a custom string installed that was thicker than stock, and I have no doubt now that that was why the bow discharged. The trigger mech was failing to fully engage the string due to the thickness of the string.