Ar50 cleaning rod or pull through

[Panzerfront]

I ordered an Otis military cleaning kit for a Barrett,but in the pics the accessories like the slotted end that screw into the pull cable look like they are made of steel,I'm afraid of scratching the barrel on my Ar50..should I search out a carbon fiber cleaning rod?or stick with the pull through?the Otis cleaning kit accessories are also threaded 10-32,not many pull through accessories thread that big...first post on here...thanks for advice