How to find your rate of twist:
Measure it yourself...
Place a patch (oiled) on a cleaning rod and run it down the muzzle. Make sure the patch is a tight fit to the bore so that the cleaning rod turns as it moves down the barrel. After the patch reaches the chamber, reverse directions and begin pulling the cleaning rod back out again - slowly. STOP when the rod starts to turn again, and place a dot on the cleaning rod at the end of the muzzle. Put your mark at 12 o'clock on the rod. (Aligned with the front sight.)
Slowly and carefully pull the cleaning rod out of the muzzle, letting it turn on it's own while watching your mark. When the dot makes one complete turn and lines up with the front sight again - STOP pulling. Put another dot on the cleaning rod at the muzzle, again at 12 o'clock. Go ahead and remove the cleaning rod from the barrel.
Measure the distance between the two dots on the cleaning rod with a tape measure. That will be your twist rate. For example, if you measured 12 inches, your twist rate is 1:12 (one turn in 12 inches.)
If you measure 8 inches between the dots, your twist rate is 1:8 and so on......