Difference In .223 Rem & 5.56 Nato ?

[perrysho]

I see info not to shot 5.56 in a .223 Rem chambered rifle but one can use .223 Rem in a 5.56. Is there a difference in the case dimension??

Just getting ready to shoot 3-Gun. Want to re-load .223 Rem Accurate 2520 Federal primers Hor 55 gr FMJ-BT W/C.

Could some one give me a starter load, was thinking about maybe 22.5 Gr, does that sound about in the ball park??

Thanks, be SAFE,

Perry

[Corey]

Its mainly a pressure issue. Shooting .223 in a 5.56 chamber is fine. Don't try it the other way around.

For the Hornady bullet, I'd check their loading manual for starting and max loads. I don't shoot that powder, so I can't help you much there.

[Cotys]

Pressures and chamber dimensions are different. The .223 has a SAAMI max of 550000 psi (50,000 CUP), NATO 5.56 has a max of 62366 psi (60,000 CUP). The 5.56 is throated longer to handle heavier, longer bullets like the M855 ball 62 grain and MK 262 77 grain. SAAMI says 223 chambers are tighter and have a shorter throat(leade).

I think it is fine to shoot .223 in a 5.56, I have done it a lot. I would not shoot 5.56 in a 223, especially heavy bullets. With that said, here's SAAMI's take in regards to 223 & 5.56: "SAAMI recommends that a firearm be fired only with the cartridge for which it is specifically chambered by the manufacturer."

The Hornady manual doesn't list a load for Accurate 2520. The Accurate web site lists quite a few 2520 and 55 gr loads, but not one for the bullet you listed.

Your load sounds light. QuickLoad estimates it at 2400 fps at the muzzle of a 16" rifle. For similar weight bullets Accurate shows 23.4 to max of 26.7 or so.

I am a member of AmmoGuide online. There are several loads listed, but not your bullet. They are showing a max of 26.4 and 26.5 range.

Edited March 9, 2012 by Cotys

[Graham Smith]

A lot of so called .223 ARs are chambered for 5.56 so double check what you have. If you are reloading, you will be probably be reloading .223 any way, unless you go out of your way to get 5.56 components.

[perrysho]

Gentlemen,

Thanks for your info/response.

Usta shot Silhouette In the 70s, but have not loaded rifle ammo in a long time.

Want to be safe, about all I could find was start about 22.5 or 23.5 Gr.

I have a Chrono and all the right equipment.

Thanks Be SAFE,

Perry

[Alaskapopo]

Pressures and chamber dimensions are different. The .223 has a SAAMI max of 550000 psi (50,000 CUP), NATO 5.56 has a max of 62366 psi (60,000 CUP). The 5.56 is throated longer to handle heavier, longer bullets like the M855 ball 62 grain and MK 262 77 grain. SAAMI says 223 chambers are tighter and have a shorter throat(leade).

I think it is fine to shoot .223 in a 5.56, I have done it a lot. I would not shoot 5.56 in a 223, especially heavy bullets. With that said, here's SAAMI's take in regards to 223 & 5.56: "SAAMI recommends that a firearm be fired only with the cartridge for which it is specifically chambered by the manufacturer."

The Hornady manual doesn't list a load for Accurate 2520. The Accurate web site lists quite a few 2520 and 55 gr loads, but not one for the bullet you listed.

Your load sounds light. QuickLoad estimates it at 2400 fps at the muzzle of a 16" rifle. For similar weight bullets Accurate shows 23.4 to max of 26.7 or so.

I am a member of AmmoGuide online. There are several loads listed, but not your bullet. They are showing a max of 26.4 and 26.5 range.

There is .223 loads with heavy bullets like Hornadys 75 grain TAP. They make it in a .223 pressure and a 5.56 pressure version. Its nothing to do with the bullet itself but rather the pressure and the leade in the barrel.

Pat

[Smokecloud]

good read on the subject.

http://www.specializedarmament.com/content/skins/flat/popup_issue_100.html

[Guest]

In .223 AA2520 works great with the heavier bullets, but it can be used with the 55gr FMJs, too. IMHO - I think your starting point is a little low. I'd start somewhere in the 23.5 - 24.0 range and work up from there. But, consult the Accurate Arms reloading book and cross verify with other sources if you can.

Be aware that federal primers are a little on the soft side and need to be fully seated in the primer pockets of brass that either doesn't have a crimp, or has had the crimp removed. I went through a spat of doubles that was traced back to federal primers that were seated in crimped primer pockets that weren't un-crimped. (yeah, that wasn't a good thing to do, but I was young and foolish.) Just make sure they are fully seated in properly processed brass and you should be OK.