Perhaps now days, most LEOs would have a Taser and use it. If not the old kick in the gonads would do it for both LEOs and Military. Of course, there are the ASP type clubs too; however. with rifle/carbine in hand this isn't easy to do either.
Yes, the M-1 Garand or M-14 would be great for a butt stroke; however. I wouldn't trust an M-16 type weapon to do the same job as they would. I'd be more apt to use the muzzle pokes to the solar plexus or face/head.
Perhaps, we should think about fixing bayonets in the military, when on patrol in areas where close contact with people is common. Nobody likes the idea of getting stuck with the old "cold steel!"
Kicks are great; however, IMHO they often expose one to a lot of good defensive tactics by the subject.
There is also MACE or Pepper canisters that could be used; however, I have witnessed the use of these weapons many times, where the gas blew or bounced back into the face of the person using it. One has to be careful when using these.
Of course, there is always the 3 Cell Mag-light!