Nothing, the sites on the puma are perfect for Cowboy Action. Put the front site dot right in the bottom of the "V" of the rear site and Bob's your uncle. This nifty rear site allows for super quick target acquisition. When shooting at 18" x 18" steel plates at 15 yards (most common distance), you really only need to just see the front site anywhere between the V up rights of the rear to hear it go "gong!!!". There will be no 50 or 100 yard shooting in SASS. If in the odd case you have a longer than 15 yard shot, just get the front site further down in the V, that's it. Just practice with the gun, you'll see what I mean.