Ok one last question for the night. If you fireform your 223 ammo in your 5.56 chamber and then reload it using 5.56 dies can you reload to 5.56 specs and pressures. Will it take up the difference in the throat of the barrel and reduce what little wear that happens because of the difference? Supposedly 5.56 brass is thicker with a slight amount of reduced powder capacity. If you start with 223 and end up with 5.56 you will do away with the thicker case walls and therefore increase your powder capacity or am I just overthinking this as my Dad says?
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Reloading 5.56 ammo question
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SSgt M
Member
Your theory sounds good, as you only need a couple thousandths to be at 5.56 spec. but I don't believe loading 223 to full 5.56 specs is a good idea, I may be wrong, but I do no fact, lake city 5.56 brass is harder and thicker than 223 federal.
Load up a few different batches and see how theu shoot, start light and work the loads up. If they don't perform at the distance you require, try something else, lots of homework will get you far, as deciding best powder type, bullet weight, miminimum case length etc.
Load up a few different batches and see how theu shoot, start light and work the loads up. If they don't perform at the distance you require, try something else, lots of homework will get you far, as deciding best powder type, bullet weight, miminimum case length etc.
Dragon88
Member
You are overthinking this one.
The differences between the two specs are primarily in the MAP (Maximum Average Pressure), freebore diameter, freebore length, and leade. 5.56 NATO specs are not achieved through the dies, they are achieved through the loading recipe. So what you are asking about is essentially an invalid question.
Case wear can be reduced by carefully tuning headspace, but this is not done through blindly full length sizing with a die. It is done by gauging your individual chamber and sizing down a specific amount to set the shoulder and headspace exactly where you want it. This is generally not a recommended practice for semi-automatic ARs. Single loading rounds into an AR for slow fire match shooting is a different story, as you take magazine length and reliability of feeding out of the equation.
Lake City brass is very high quality and stronger than, say, Federal. However, it's not due to case thickness. It's due to quality of the brass and proper annealing. The requirement to load down for military brass due to case thickness is more of a concern for the .30 caliber service rounds, not 223/5.56.
Lastly, do you have 5.56 NATO load data? Where did you get it from? Nearly all civilian load data for this cartridge is limited to the 223 specification for safety reasons. Handloading to full 5.56 NATO pressure is unnecessary and unsafe unless you can gauge actual pressure. Most of us do not have access to pressure testing equipment to do that.
The differences between the two specs are primarily in the MAP (Maximum Average Pressure), freebore diameter, freebore length, and leade. 5.56 NATO specs are not achieved through the dies, they are achieved through the loading recipe. So what you are asking about is essentially an invalid question.
Case wear can be reduced by carefully tuning headspace, but this is not done through blindly full length sizing with a die. It is done by gauging your individual chamber and sizing down a specific amount to set the shoulder and headspace exactly where you want it. This is generally not a recommended practice for semi-automatic ARs. Single loading rounds into an AR for slow fire match shooting is a different story, as you take magazine length and reliability of feeding out of the equation.
Lake City brass is very high quality and stronger than, say, Federal. However, it's not due to case thickness. It's due to quality of the brass and proper annealing. The requirement to load down for military brass due to case thickness is more of a concern for the .30 caliber service rounds, not 223/5.56.
Lastly, do you have 5.56 NATO load data? Where did you get it from? Nearly all civilian load data for this cartridge is limited to the 223 specification for safety reasons. Handloading to full 5.56 NATO pressure is unnecessary and unsafe unless you can gauge actual pressure. Most of us do not have access to pressure testing equipment to do that.
Thanks Dragon....And Sarge...I have performance Specs and powder types, I can work up from those, mostly using a chrony. My 8x57 loads are loaded more to European Specs, if I load to SAMMI specs I can almost outrun my bullets. I have thought about it and I have decided to reload for my AR, I started out buying 223 ammo and then after shooting some 5.56 I truly noticed a difference in accuracy. I have been buying lately only brass cased 5.56 and I do realize that unlike my bolt action rifles where I measure a lot of things to match the round to the weapon on my AR it is mostly going to be to make them all as close to a standard round that I can. But I wondered, and I am sure I can come up with some load data for 5.56, but you all are right. I just need to start and work up a load that does what I want it to, and then load to that standard. Thanks for your time.
To organize some of what is said above better:
The major differences between .223 Remington and 5.56 x 45mm are in details of the chamber the rounds are fired in and in the allowable pressures. 5.56mm has a higher allowable pressure since the muzzle velocity spec was determined at 78 feet (prior military practice due to limitations on measuring equipment way back when) rather than the 15 feet usual with SAAMI. The 5.56mm ammo suppliers needed to jack up chamber pressures to make specified velocity at the required distance. If you're thinking that difference isn't many fps, you're right.
Without access to the actual cartridge specifications, I doubt there's a measureable difference in the cartridge dimensions. I couldn't find 5.56 dies as a separate item for reloaders. Depending upon brand of case, there may be a difference in thickness of the brass between the two cartridges. Federal makes both .223 and 5.56 cases to the same thickness/weight (what matters is they have the same capacity). I have no knowledge about any supposed differences in brass hardness or metallurgical differences between the two.
The reason you see warnings not to shoot 5.56mm in .223 chambers is because the 5.56mm allows a chamber pressure above SAAMI maximum for .223 and the tighter .223 chamber can cause that pressure to go even higher.
Short form: Yeah, you're way overthinking this. Pick a load that shoots well in your rifle and quit worrying about microscopic stuff that doesn't matter and that you can't change.
Differences between SAAMI & CIP load specs for european cartridges are mainly political. After all, you don't want the customer base to be able to pick up a surplus rifle for $20 (1947 prices) that's as good as a new $65 local product. That's why you seen many 8x57 loads that are real close to .30-30.
The major differences between .223 Remington and 5.56 x 45mm are in details of the chamber the rounds are fired in and in the allowable pressures. 5.56mm has a higher allowable pressure since the muzzle velocity spec was determined at 78 feet (prior military practice due to limitations on measuring equipment way back when) rather than the 15 feet usual with SAAMI. The 5.56mm ammo suppliers needed to jack up chamber pressures to make specified velocity at the required distance. If you're thinking that difference isn't many fps, you're right.
Without access to the actual cartridge specifications, I doubt there's a measureable difference in the cartridge dimensions. I couldn't find 5.56 dies as a separate item for reloaders. Depending upon brand of case, there may be a difference in thickness of the brass between the two cartridges. Federal makes both .223 and 5.56 cases to the same thickness/weight (what matters is they have the same capacity). I have no knowledge about any supposed differences in brass hardness or metallurgical differences between the two.
The reason you see warnings not to shoot 5.56mm in .223 chambers is because the 5.56mm allows a chamber pressure above SAAMI maximum for .223 and the tighter .223 chamber can cause that pressure to go even higher.
Short form: Yeah, you're way overthinking this. Pick a load that shoots well in your rifle and quit worrying about microscopic stuff that doesn't matter and that you can't change.
Differences between SAAMI & CIP load specs for european cartridges are mainly political. After all, you don't want the customer base to be able to pick up a surplus rifle for $20 (1947 prices) that's as good as a new $65 local product. That's why you seen many 8x57 loads that are real close to .30-30.
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SSgt M
Member
SSgt M
Member
case .223 Remington Case type Rimless, bottleneck
Bullet diameter .224 in (5.7 mm)
Neck diameter .253 in (6.4 mm)
Shoulder diameter .354 in (9.0 mm)
Base diameter .376 in (9.6 mm)
Rim diameter .378 in (9.6 mm)
Rim thickness .045 in (1.1 mm)
Case length 1.76 in (45 mm)
Overall length 2.26 in (57 mm)
Rifling twist 1 in 12 inch (military style rifles use 1:7 to 1:10 to stabilize heavier bullets) Primer type Small rifle Maximum pressure 55,000 psi (380 MPa)
Bullet diameter .224 in (5.7 mm)
Neck diameter .253 in (6.4 mm)
Shoulder diameter .354 in (9.0 mm)
Base diameter .376 in (9.6 mm)
Rim diameter .378 in (9.6 mm)
Rim thickness .045 in (1.1 mm)
Case length 1.76 in (45 mm)
Overall length 2.26 in (57 mm)
Rifling twist 1 in 12 inch (military style rifles use 1:7 to 1:10 to stabilize heavier bullets) Primer type Small rifle Maximum pressure 55,000 psi (380 MPa)
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SSgt M
Member
5.56 NATO Case type Rimless, bottleneck
Bullet diameter 5.70 mm (0.224 in)
Neck diameter 6.43 mm (0.253 in)
Shoulder diameter 9.00 mm (0.354 in)
Base diameter 9.58 mm (0.377 in)
Rim diameter 9.60 mm (0.378 in)
Rim thickness 1.14 mm (0.045 in)
Case length 44.70 mm (1.760 in)
Overall length 57.40 mm (2.260 in)
Case capacity 1.85 cm³ (29 gr H 2 O)
Rifling twist 178 mm or 229 mm (1 in 7 in or 9 in, originally 1 in 14 in) Primer type Small rifle Maximum pressure 430.00 MPa (62,366 psi)
Bullet diameter 5.70 mm (0.224 in)
Neck diameter 6.43 mm (0.253 in)
Shoulder diameter 9.00 mm (0.354 in)
Base diameter 9.58 mm (0.377 in)
Rim diameter 9.60 mm (0.378 in)
Rim thickness 1.14 mm (0.045 in)
Case length 44.70 mm (1.760 in)
Overall length 57.40 mm (2.260 in)
Case capacity 1.85 cm³ (29 gr H 2 O)
Rifling twist 178 mm or 229 mm (1 in 7 in or 9 in, originally 1 in 14 in) Primer type Small rifle Maximum pressure 430.00 MPa (62,366 psi)
