Deer Hunting with 5.56

Going with my dad this October in Flagstaff i just read this article:

Who has taken deer with 5.56 and what bullet did you use?


Sounds like you’re going to have some fun.
All the deer and hogs I have ever taken have been with Hornady.

Turns 'em into a spinner real quick.

Note: as a reloader 556 and 223 are exactly the same round. Weight, powder - volume and type.


@Fizbin I’ve read there is a supposed gain of 10,000 psi, do you think its a marketing gimmick?

I think it’ll be fun for me, my dad and two teenage sons. My dad has cooler rifles for hunting in larger calibers but all I have to train is the AR which is better for my sons to take a shot anyway. We have to train though since its our first hunt (me and my boys) and 6000 feet gain in elevation.


I’m not sure what you’re referring to on the 10kpsi, between a 556 and 223? There should not be. The same powder, primer, bullet head, shell casing are used.

Some say a 556 has a different rifling than a 223 rifle. I’m not sure on that, all I know is the round is exactly the same. I’ve hit hog with the AR as my perceived penalty of a miss is pretty low. A deer or “real game” I use a bolt with a longer barrel and big big scope. I don’t want a deer to suffer or for me to have to go tracking it.

That sounds like some nice elevation, dress warm. :slight_smile:


I wouldn’t want the deer to suffer either or me having go looking for it a far distance either since it’ll be very cold around that time.

The scope he recommended is:

About the rounds I read this article: 5.56 vs .223: What's the Difference? Does it Matter? - The Truth About Guns

But again I don’t know much and believe you since you reload and I don’t, it seems like 5.56 is just a hot round like a 380 +P matches the power of regular 9mm ammo as long as the grain is the same and are shot from the same length barrel.

I will for sure be dressing in layers, its just a 2 hour drive but the change in environment is pretty extreme.

Roger that on the deer tracking… That’s what some of the handheld thermals help with.

The scope, I am an all American Made type person. From my blue jeans to my ammo, to my scopes and more. Yes, I pay a bunch more but I will NOT give money to China. The Vortex are way cheaper but are made in China. This is the glass I have on my rifles.

Note, I don’t buy from the monster Amazon anymore either.

The 223/556 data I use comes from this book. I think my addition is #5, to tell you how long I’ve been reloading. The 223 will get the job done, bullet placement goes a long way.

I read your article and they talked about “hotter” but the amount and type of powder is still the same. They did about C.O.L. without actually calling it that. That stands for Cartridge Overall Length. being that the casings are all the same the only way to change the COL, when using the same bullet head, is to seat the bullet either deeper or shallower. If you do this and then cron the shot, you will see a difference in velocity. Too much either way is not good, and not recommended in the Handbook.

Just some overall cool info above. I’ve even hit hog using less than impressive (so to speak [junk ammo]) 223 ammo and with a well place shot the hog still spins.


Thanks for all the info on the bullets and I agree with not giving money to China. I work at Amazon and wish we blocked more Chinese sellers like we’ve done recently since they are unethical and more third party sellers sold things made in the US and this part of the world. I also think a new retailer should compete with Amazon with only American made products.

About the scope I found one made by that company comparable to the vortex one: Leupold VX-Freedom Rifle Scope 3-9x40mm Custom Dial System (CDS) ill happily give my money to an american company for a few bucks more.


10 4

That is a good scope and a good price. You’ll have it forever.

My pleasure helping out. I really enjoy all the folks on this forum and love interacting with them.
Don’t forget to get some SD training in your area. The USCCA Defensive Shooting Fundamentals course is very very important to your overall safety.


I have no experience using .223 on deer but I have been reading up on the subject because I think .223 with the right bullet would be a good starter hunting round for my son when he gets older. Along with @Fizbin ‘s recommendation it seems a lot of folks have had success with the Speer Gold Dots in 75gr and 62gr. They are my go to SD round so I am thinking of giving them a try on deer next year to make sure they will do the job. I will be keeping my shots under 100 yards though since I wouldn’t feel comfortable using .223 on a deer beyond that distance.

I do actually have a fair amount of first hand knowledge about Flag though living not too far down the road from there. The altitude can definitely slow you down if you’re not used to it. What Zone did you get drawn for?


I think he has zone 6A unfortunately I did not get drawn for deer. I’m just doing an OTC for Javelina and hopefully we see some in that zone or If we change the dates to December I can do elk (With his rifle since 5.56 vs 600-800lbs elk isn’t adequate) if still OTC for 6A and him deer.


Actually my hornady reloading manual has separate data. P M me if you want photos.

1 Like

I’ve used these for several whitetail and all the way down to bobcat.

A coworker started his son on whitetail with the federal fusion load.

I’d recommend you download the app called BulletDrop +
It’s around $2 and adjustable for elevation and other factors. You will also see how fast the energy drops off with the little 223 cartridge.


Think I’ve read that the Federal Fusion and the Speer Gold Dots use the same bullets.

1 Like

6A covers some pretty interesting country. The only hunting I’ve done down there is for ancient ruins and old mines. I’ve run into quite a few Javelina around those parts. Heard they don’t taste very good so haven’t tried hunting them. Though on my one and only elk hunt I had 3 of them almost bump right into me while I was waiting for the elk to come along. I was down wind and think they must have very poor eyesight.


Yes, the cases on the 5.56 and .223 are slightly different and can have different pressures. That’s the endless debate on shooting 5.56 in .223 barrel and vice versa.

From one source (there are numerous on the Internet and some that address the actual case dimensions and pressures), Palmetto State Armory:
Can you shoot 5.56 NATO out of a .223 Remington? No.

The difference that matters most is the fact that the design of the 5.56 NATO round and *the chamber results in a higher pressure than the .223 Remington round.

American Rifleman says:
"The 5.56x45 mm surfaced in 1957 as an experimental cartridge in the AR-15 rifle. The concept was to develop a smaller, lighter military cartridge that would still be traveling faster than the speed of sound at 500 yards, and this was accomplished by using a 55-gr. boat-tail bullet. The AR-15 evolved into the select-fire M16 rifle that was adopted by the military in 1964.

Remington was quick to act, and very shortly after the military adopted the 5.56x 45 mm cartridge the firm brought out the civilian version, called the .223 Remington."

The higher pressure of the round is the result of design differences between the 5.56 and .223 respective cases. There are subtle dimensional differences in the cases of the rounds and the throats of the barrels (known as the leade) made for each respective round.

[T]he 5.56 NATO has by design almost twice the leade that the .223 Remington does. So, a cartridge designed for a long bullet jump, or leade, which is fired out of a chamber with a shorter leade as is the case when firing 5.56 NATO ammunition out of a .223 Rem. The chamber can result in a fast and dangerous pressure spike. Again, firing lower pressure .223 Rem. ammo from a 5.56 NATO chamber is no issue


I believe 556 is loaded to higher pressure than 223 but the external dimensions are the same. 223 Remington chambers are cut tighter than 556 chambers. 556 chambers have more freebore Before the lands, similar to chambers in Weatherby rifles. The running start allows for higher operating pressures while keeping it safe. That’s why it’s fine to fire 223 in a 556 chamber but not the other way around.

Look into 223 Wylde chambers for more understanding of it. The Wylde is a compromise between the two and is safe to fire either ammunition in. It’s tighter than 556 though for better accuracy potential.

The problem is that actually you can because they have the same external dimensions. Doing so will cause severe pressure spikes and damage!!!

Just like certain deep seated 300 blackout rounds can be chambered and fired in 556 but with catastrophic results trying to squeeze a 30 caliber bullet into a 22 caliber hole.


I have not and would not. But that’s just me.

Yes, that is correct in the external dimensions are the same, however case capacities differ. As previously stated, the pressures are different and very important, as are the leades, which is why one should not, though can, fire 5.56 in .223, as @Barry54 stated. I did not feel it worth expounding on that it is physically capable to do so, just potentially gravely unsafe. I am not a rifle shooter, so my information is only based on what I have read, and it had been a while since I read about the topic. I apologize for getting one of the facts wrong. I should have sourced that, first, as I typically do.

From the Ultimate Reloader:
The case capacity is also slightly different:

  • 5.56 NATO case capacity: 28.5 grains H2O
  • 223 Remington case capacity: 28.8 grains H2O (+1.1% compared to 5.56 NATO)

As with most factors related to 5.56 and 223, actual case capacity will vary. In summary: the exterior dimensions of 223 Remington and 5.56 NATO ammunition are essentially the same […] perhaps with 1% difference in case capacity between the two.

223 Remington Cartridge Diagram:

5.56 Nato Cartridge Diagram: