Actually gathering 223 on ghouls with a sniper character armed with a sniper rifle is very easy, you use 1-2 bullets per ghoul, actually when I go for ammo hunting on ghoul crazies i use 8-12 223 bullets to kill the AR and HR crazies, and don't bother with the rest carrying out of the encounter 30+ rounds +HR's and AR's.
Changing the ammo in the HR will generate a problem withe the 223 pistol like mentioned before, i suggest changing the ammo in HR to new 0.308 cal (springfield rifle?), and replace the HR required to craft 223 pistol with a sniper rifle, because, like mentioned before, it's an end game pistol, and HR is to easy to get.