5.56 vs .223

[bongfoo]

ok, i've got a question... up untill now i've only reloaded .223. is 5.56 any different? i've heard that the case dimensions are different between the two. my question is this:

When Trimming the case should they be trimmed for OAL or should i trim 5.56 off the neck?

[joelogic]

There are no 5.56 dies but you could try and load to that pressure.

The second question, did you mean shoulder?
Either way you trim to oal.

[ExtremeX]

I was under the impression it’s the same thing except the different maximum SAMMI pressures one would be loading to.... but that’s just my assumption.

[GeoffLinder]

ok, i've got a question... up untill now i've only reloaded .223. is 5.56 any different? i've heard that the case dimensions are different between the two. my question is this:

When Trimming the case should they be trimmed for OAL or should i trim 5.56 off the neck?

Case dimensions are the same for .223 and 5.56. The difference is in the rifle chamber/throat. .223 has a shorter leade and chambers are usually a bit tighter. 5.56 usually has a looser chamber cut to allow for more functioning leeway when dirty and also has more leade area ahead of the chamber to allow for safer pressures and longer bullets like tracers, etc.. This prevents ammo from getting the bullet jammed into lands on chambering and the longer bullet jump helps control higher pressures present in most military ammo.

Commercial .223 ammo is safe in either chamber, 5.56 ammo is not always safe in a .223 chamber. Only real difference is in the pressure the ammo is loaded for. SAAMI pressure spec for .223 ammo is about 58000 CUP and about 62-63000 CUP for 5.56.

Cases are trimmed for case length, not loaded ammo length (OAL), case trimming has nothing to do with OAL of loaded rounds. Trim to length for .223/5.56 cases is 1.750" You do not want to use cases with length much over 1.765" or you risk creating an overpressure situation when longer case neck gets jammed into end of chamber and increases bullet release tension and causes pressure rise.

Joe is correct in that there is no such thing as 5.56 dies, all dies are .223. For reloading purposes .223 is the same as 5.56.

Joe is a little bit incorrect in his reference to trimming to OAL (OAL meaning loaded length of bullet and case combined). OAL and unloaded case length are two different things. OAL should always be used to refer to the length of a loaded round from case head to bullet tip. Case length is from case head to case mouth of an unloaded case and should be referred to separately from OAL.

[joelogic]

Ah, I stand corrected. Trim to case length.

[EL_NinO619]

Case dimensions are the same for .223 and 5.56. The difference is in the rifle chamber/throat. .223 has a shorter leade and chambers are usually a bit tighter. 5.56 usually has a looser chamber cut to allow for more functioning leeway when dirty and also has more leade area ahead of the chamber to allow for safer pressures and longer bullets like tracers, etc.. This prevents ammo from getting the bullet jammed into lands on chambering and the longer bullet jump helps control higher pressures present in most military ammo.

Commercial .223 ammo is safe in either chamber, 5.56 ammo is not always safe in a .223 chamber. Only real difference is in the pressure the ammo is loaded for. SAAMI pressure spec for .223 ammo is about 58000 CUP and about 62-63000 CUP for 5.56.

Cases are trimmed for case length, not loaded ammo length (OAL), case trimming has nothing to do with OAL of loaded rounds. Trim to length for .223/5.56 cases is 1.750" You do not want to use cases with length much over 1.765" or you risk creating an overpressure situation when longer case neck gets jammed into end of chamber and increases bullet release tension and causes pressure rise.

Joe is correct in that there is no such thing as 5.56 dies, all dies are .223. For reloading purposes .223 is the same as 5.56.

Joe is a little bit incorrect in his reference to trimming to OAL (OAL meaning loaded length of bullet and case combined). OAL and unloaded case length are two different things. OAL should always be used to refer to the length of a loaded round from case head to bullet tip. Case length is from case head to case mouth of an unloaded case and should be referred to separately from OAL.

You are absolutely spot on... Except.... https://shop.rcbs.com/WebConnect/Mai...productId=6243

But its just a marketing gimmick.

[GeoffLinder]

Ah, I stand corrected. Trim to case length.

No problemo Joe, just don't want to scare the horses or confuse the newbies

[bongfoo]

geo, you are correct. i was a bit tipsy last night when i asked this question. i meant OACL, not OAL. but you summed up what was running through my head about the pressures. you also added a litle about the chamber dementions that is a good little tidbit to know. thanks!

[russt]

It's ok to post while tipsy, just don't load while tipsy!

[GeoffLinder]

It's ok to post while tipsy, just don't load while tipsy!

Ore even better don't shoot what you load while tipsy, just give it to your friends to test LOL

[GeoffLinder]

geo, you are correct. i was a bit tipsy last night when i asked this question. i meant OACL, not OAL. but you summed up what was running through my head about the pressures. you also added a litle about the chamber dementions that is a good little tidbit to know. thanks!

No problemo :-) Thank you, AND you are very welcome!