I have not heard of anyone shooting a 10twist 6.5 creedmoor. With the odd exception, just about everyone shooting the 6.5 CM has an 8 twist barrel.

Take a nylon bore brush on a cleaning rod and run it through the barrel to figure out the real twist...

Insert brush in the barrel...
Once the brush starts to spin, stop and make a mark on the cleaning rod,
Take a tape measure and measure from the receiver (or the bore guide mouth) to the cleaning rod handle,
push the rod down the bore and stop once the mark you made makes a full revolution,
then measure from the same point to the handle.
Subtract the smaller # from the bigger and you get your true twist.

Simple and conveniently done when cleaning the barrel.

I wouldn't shoot anything heavier than 120gr in a 10 twist 6.5 Creedmoor.