Hornady Manufacturing recently announced an expansion to its Critical Duty line with a new 9mm load. The new load uses a 124 gr FlexLock bullet that is lighter than the previous 135 grain offerings in this line. The 124 grain Critical Duty load is loaded to “+P” pressures. Existing 135 grain loads are offered in both standard and +P pressure levels.
Typically, increased pressure levels are used to drive higher bullet velocities. In this case, the 124 grain +P load is expected to have a muzzle velocity of 1,160 fps when it ships. This compares to 1,010 fps and 1,110 fps of the existing standard and +P 135 grain loads.
In general, velocity is a tool that is used by bullet designers to ensure expansion. Combined with the polymer plug typical to the FlexLock bullet design, I would expect that the design team was able to get these rounds to expand reliably.
Many shooters like the Critical Defense load for a concealed carry ammunition. The Critical Defense load is designed for a different set of purposes. First, it was developed to achieve optimal performance in full size handguns. Smaller pistols, like those often carried for self-defense, may not be ideal for the Critical Duty line.
Another major design characteristic of this line is its ability to penetrate barriers. The FBI testing protocol provides a repeatable evaluation standard for comparing one ammunition load against another in a set of very specific performance measurements. It is biased toward ammunition that penetrates intermediate barriers such as auto glass and metal. This load is designed to perform well in that testing.