I'm finishing up my cmp hellcat and i need to balance it,my problem is the balance point is 120-135mm,and i have not metric measuring device,does anyone know what this would be in inches?Man,i really appreciate the help,dont want to mess this part up.

1 inch = 25.4 mm

You can take the values listed in metric and divide them by 25.4 to convert them to inches.

use the ring guage of a robusto about 3 times

good luck on her maidend Mike. be sure to post pics

Thanks guys,my math stinks,i hardly use the metric system.

Math will get you far in life, my friend. One cannot build or fly an airplane without mathematics.