The 68 Specials had a tendency to chop a ball if you were firing fast. This was due to the open breach on the left side of the gun. The open breach was so you could send a squeegee through it and squeegee the barrel with out taking off the barrel. Back in the day people would rap a rubber band around the breach to form an "X" over this hole to keep the balls from getting pinched there. There was also a company that would bore out the breach and install a sleeve into the breach to cover up the hole.

There are a lot of 68 Specials that are converted SMG's Tippmann offered to convert them to keep up with the times. This is one of the reasons why the SMG's fetch a higher price than the 68 Specials.