The year was 1968, the place was Chu Lai, Vietnam. I ran the bulldozer in the garbage dump, my second job was to kill stray dogs that came to the dump to eat, because we had a rabies problem on the base I was told. I shot a few dogs with a M-16 and got to look at the wounds, most took two or MORE hits to the chest area to drop (no head or spine shots because of the rabies). All the wounds I saw were 22 in and just about 22 out, no tumbling.
AWS
A little added info. The year was 1967, the place Taipei, Taiwan. Having some good friends working in the armory at Linkou air station I had a good supply of the then new M-16 ammo. I orderred (from the Embassy Gun Shop) the first .223 bolt action rifle they could get their hands on. It turned out to be a Rem. 600 (never catalogged in .223) it set me back $49.00. I shot ALOT of military ammo at paper at 50 to 600 meters (chinese army range), no tumbling there either. I still shoot that rifle, the rib is gone and the stock shortend and reshaped, it has been my favorite calling rifle for a long time.
AWS