A 5.56 caliber round will kill a deer. Even without a perfect shot either a 75-grain or 77 grain 5.56 round carries enough force to put down a deer. However, you want to ensure you use bullets designed for hunting the BTHP line from Hornady, Nosler and Black Hills with their new 77 Grain MK 262 Mod 1-C.
The Difference of a 5.56 and a .223
There is some confusion among many shooters that a 5.56 and a .223 are the same thing. While they are very similar in size, and in fact many rifles will fire both calibers, there are some slight differences.
For this reason if you are wanting maximum performance when attempting to hunt deer with a 5.56 make sure that you select a round specifically made to fit that caliber.
You should not fire high powered 5.56 rounds in a .223 chamber. The 5.56 was designed to withstand 3000psi more pressure than the .223. Using 5.56 rounds in a .223 could result in higher than normal stresses on the weapon and catastrophic failure of the chamber housing.
The Weight of a 5.56 For Killing a Deer
Often considered to be too small or inhumane when used for deer hunting it is important that you select ammunition that is heavy enough to transfer the needed force into the deer you intend to kill.
While a 55 gr bullet may do the job under optimal conditions it is recommended that you start in the mid 60s on grain weight with optimal being the variants offered in 75 gr and 77 gr.
There is a 112 grain bullet made by Atomic and several other companies. However, these are subsonic in velocity traveling at around 1000 to 1050 fps compared to the 2300 to 2500 fps common with the 75 grain bullets.
Having not tested these 112 grain bullets myself I expect that the lower velocity of the round coupled with the increased mass will result in less overall energy delivered to the target and some loss in accuracy.
Legally Can You Use a 5.56 or .223 to Kill a Deer?
This is going to depend largely on your state’s laws. Links to each state’s hunting regulations are located here.
You can legally use a 5.56 to kill deer in the following states.
|Nebraska||Nevada||New Hampshire||New Mexico|
|New York||North Carolina||North Dakota||Oklahoma|
|Oregon||Pennsylvania||South Carolina||South Dakota|
The remaining states either require a larger caliber round or do not permit hunting with modern rifles.