Hey guys!
I'm new to the party, and was reading comments about knowing rate of twist and not knowing how to find that out.
Here is how I was taught back in the Jurassic period.
Find a brush or mop that fits snug enough in the barrel that it will twist in the rifling without slipping.
Somewhere convenient back on the cleaning rod, place a piece of tape that sticks out like an arm on the rod. insert the brush/rod into the bore far enough into the muzzle, yes the muzzle, that you know it is engaged. Mark a line at the muzzle on the cleaning rod. Push the rod into the bore until the piece of tape you mounted back on the rod has made one full rotation. Mark the rod again. Pull out the rod and measure the distance from the first mark on the rod to the second mark on the rod.
Not micrometer precise, but it will be very close.