Random, I'm guessing you've been told never to insert a rod from the muzzle end of the barrel to avoid damaging the crown. That is certainly good advice for cleaning, and when you have reasonable access to the chamber end of the barrel. But with many guns, it is just not practical to insert a rod from anywhere but the muzzle. This is an area to apply some common sense.
There is a big difference between running a rod back and forth when cleaning and inserting a rod as a probe, once, carefully.
There is no likelihood of muzzle damage if you use a wooden dowel, or a brass one, again carefully.