Could you kindly backup the other affirmation you made? Where the fact that since the cartels have better weapons, the DEA is having to upgrade theirs. Of course you'll find evidence of new weapons being used by the DEA / Border Patrol, but I'd like to see evidence that this is caused / required by the cartels having newer, better, badder weapons.
I know that the US/Mexico border is a very hostile environment but I don't believe it has reached the point of an arms race. The cartels don't cross the border in a way (facing and engaging the border patrol, like it would be in a war zone) that would justify the need for even more weapons on the US side. If it were so, then probably the US Military would have gotten involved already, instead of having to frequently upgrade the Border Patrol / DEA arsenal.