[Tree climber]

can I use this nock in replace of this nock for a bear constrictor CDX crossbow

 

[bunnyrabbit]

Both pictures of the nocks you submitted are 1/2 moon. The lower picture has the sides
of the nock sloped for a possible easier bow string angle. One could cock the crossbow
and insert the other arrow to see if it properly fits the bow string in the arrow-latch area.
The nock in the lower picture appears to have a deeper groove.

Wishing you all the best with what ever you decide.
Take care.

 

[Huntersthompson]

Those truex nocks have been proven to cause separation of serving. Just use regular moon nocks.