Please note that this article looks at research and testing done by a variety of sources. Extreme caution should be taken when creating loads that go against accepted load data. This article looks at theory and our experience, and should not be considered recommendations about primers for the .223. When developing a new load for your .223, or any caliber, you should start with smaller amounts of powder and pressure and work up gradually.
What Size Primer Does 223 Take?
The .223 cartridge takes a small rifle primer. Some load data, such as Nosler and Lee recommend regular small rifle primers, while others recommend either magnum small rifle or the #41, harder magnum small rifle primers.
The Difference Between 556 and 223
Many people erroneously think that the 5.56 and .223 are the same, and that they can be loaded the same. While they use the same projectile, and are extremely similar, to the point that 5.56 rifles can shoot .223 Ammo, they are different. The 5.56 is a military round and generally runs at higher power, with more powder and more pressure. The 5.56 cartridge walls are thicker to allow for these higher pressures. Because of that, the 5.56 can shoot a 223, but the 223 cannot shoot a 5.56 cartridge.
If you want to make higher pressure 5.56 loads, we recommend sorting your brass. It can be dangerous to mix up 5.56 and .223. If you want to load them all the same, we recommend loading them all as .223.
It’s important to note that because of the differences, you may want to prime your .223 and 5.56 differently.
Can you use small rifle magnum primers in .223 reloads?
Yes, some reloading data are made with small rifle magnum primers. Loaddata.com has their .223 loads listed as taking a regular small rifle, but they have the .223 load data written up and calculated with small rifle magnum primers. Hornady also has their load data calculated with small rifle magnum primers, specifically Remington 7 1/2 primers. Magnum primers often use less powder to get the same velocities and power. If they cost the same and your manual is calculated in magnum primers, I’d use magnums. The powder savings is only a couple tenths of a grain, but that can add up.
I asked my personal gun smith, who also taught me to reload his opinion on small rifle vs small rifle magnum and this is what he said about it: “I’ve tried both. Small mag is if you want fast loads. You need to burn a lot of powder quickly. You can over pressure the case quick so be careful. I have also seen some mag loads for subsonic because you are using a lot less powder and you want to get a big flame in there to ignite the powder. In the end if you are following good reloading procedures, load light and build up to what you want with either one.”
Can I use #41 small rifle primers in .223?
Yes. The #41’s have a harder cup and are very popular for reloaders who shoot primarily out of an AR15 platform. Most reloaders are able to use these interchangeably with the magnum small rifle primers without adjusting their load data, but you do your own testing if you choose to use the #41 small rifle primers in your .223 loads.
Will small pistol primers work in .223?
We have seen some reports that yes, many people have gotten small pistol primers to work in their .223 loads. Some report that they even chronograph at faster speeds than with small rifle primers, though we haven’t verified this.
Can I use small pistol magnum primers in .223?
We’ve also gotten reports that yes, you can also use small pistol magnum primers to develop your loads. We also read a report that said for one manufacturer, they’re identical to the regular small rifle primers:
According to Speer/CCI Technical Services – Both the CCI 550 Small Pistol Magnum and CCI 400 Small Rifle primers are identical in size. Both primers use the same cup metal and share the same cup thickness. Both primers use the same primer compound formula and same amount of primer compound. They can be used interchangeably.
Speer/CCI Technical Services
As always, do your own testing to confirm using safe load development practices.
What Primers Do I Use?
I initially developed my .223 loads using regular small rifle primers. I fine tuned it to how I wanted it, and have never had any reason to change. If its working, don’t change it.
Other Frequently Asked .223 Primer Questions:
Will small rifle primers work in .223?
Yes, the .223 is made to take a small rifle primer. Some recommend an AR specific primer, with a thicker cup, but we haven’t ever had any issue with using regular small rifle primers in a .223.
Can you use CCI 41 primers for .223?
Yes. It loads about like a regular small rifle primer. It is a popular primer in AR type rifles. If you have light firing pin strikes, you may have problems with these, as they have a harder cup, but the .223 was originally designed to shoot this harder nato style primer.
Can you use CCI 450 Primers for .223 reloads?
Yes, the CCI 450, or the small rifle magnum primers work great in a .223 cartridge. If you’re switching from a regular small rifle primer, you’ll likely need to readjust your load.
Where can I find .223 primers for sale?
I buy from Sportsman’s warehouse and several local shops by where I live.
CCI primers for .223
CCI 450, 400, and 41 primers are all the commonly used cci primers used, and there is standard load data for each. Look at your specific load data and see if what it specifies.
What Winchester Primers should I use for .223?
We recommend the WSR primer, or small rifle primers. They do have a thinner cup, at .020, so if you have a heavy striking free float firing pin, you may want to consider something like the CCI #41s.
223 Primer Size Best Possibilities
- Small rifle magnum
- Small rifle
- AR Small Rifle Primers
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