Shotguns without threading for removable chokes can have the current choke constriction opened. This procedure is very similar to back boring but is limited to the choked area of the bore. Most such shotguns have a choke constriction length of 3" to 4" and after opening this length will increase in direct proportion to the amount the choke is opened. Opening a fixed choke can allow a full choked barrel to safely shoot steel and other nontoxic shot, for example. Opening the fixed choke can also shorten the shot string.