.223 / 5.56 & 7.62x39

5.56 chambers are slightly looser than .223 chambers and have a longer throat.
Both use the same diameter projectiles. Barrel twist rate and magazine restrict the length of bullet you can use.
The external dimesions are the same or close enough to not matter.
Some like to use the CCI 41 primers for 5.56 ammunition, but I've use Winchester with no troubles in all my auto loaders. M1, M1A, AR-15 / AR-10

For the 7.62, .308 would be the safe bet until you slug your bore to get dimensions. My SKS's are .311" so I would use .310' commercial bullets if I were to reload for it.

If reloading for a chamber designated 5.56 NATO, would the projectile be any different in diameter than that intended for a chamber designated .223?

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no

And are the brass dimensions different.

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no

Also, does either one, or the other, require a different or specified primer?

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no, they both use small rifle primers.

As for the AK47, what bullet dimension would be used. I've read that .308 is applicable, but is that the only option?

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they're .312", but some folks use .308" with varying degrees of success.

gamestalker said:

If reloading for a chamber designated 5.56 NATO, would the projectile be any different in diameter than that intended for a chamber designated .223?

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Unfortunately, the folks that name their cartridges do not do us any favors.

For example, 218 Bee, 219 Donnalson Wasp, 220 Swift, 221 Remington Fireball, 222 Remington, 223 Remington, 224 Weatherby, and 225 Winchester (there are many others as well) all use jacketed bullets with a 0.224" diameter.

Then you have early 22 Hornet (0.223"diameter) and late 22 Hornet (.224 diameter).

Finally, throw in the European metric designations.

Should be clear as mud, eh?

To answer your question, 5.56 NATO and 223 Remington use the same diameter bullets, 0.224" diameter.

Some excellent reading on the .223 vs 5.56 issue.

http://www.luckygunner.com/labs/5-56-vs-223/

no, they both use small rifle primers.

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Not really. The 223/5.56 uses Small Rifle, the 7.62 x 39 uses Large Rifle except the older Rem brass used Small Rifle.

There are bullets designed for the 7.62 x 39. Most are .310.
http://www.midwayusa.com/find?sortby=1&itemsperpage=20&newcategorydimensionid=6295

Brass is the same, only presseure differences. Diameter of bullets are the same, i would only shoot jacketed out of my 223, because with lead bullets you have less powder because you dont want the bullet to fly fast because it wil deform.

Yes the primers berween 223 an 7.62x37 are 2 different sizes.

Bullets in 7.62x39, as far as i know 308-310 will be the best bullets to use.

Remember if you try and shove a lead bullet up a loading ramp in a semi auto, you will more than likely deform the bullet before you pull trigger

45lcshooter said:

Brass is the same, only pressure measurement differences.

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Fixed it for you. The differences in the leade and freebore of the chamber allow a 5.56 load to be hotter while still developing the same peak pressure as a .223 wheh using like measurement methodology.

Bullets in 7.62x39, as far as i know 308-310 will be the best bullets to use.

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Slug the bore if at all possible to determine what bullets to use for best results. Hornady and others make bullets specific to the larger .310-.312 bores that are also the standard 123gn.

Remember if you try and shove a lead bullet up a loading ramp in a semi auto, you will more than likely deform the bullet before you pull trigger

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Lot of assumptions there. Weapon design, bullet design and alloy all play a part. Making that blanket statement puts a false impression out there. There are plenty of people using cast lead in full-auto SMGs without issue. Plenty of match shooters shooting cast lead SWCs in 1911s and winning. Saying that a semi-auto is going to "more than likely" deform a bullet upon loading is way to broad a statement. I'd never shoot lead in a gas gun just because I wouldn't want lead in the gas system not because I'm worried about the bullet possibly getting a slight rub. FWIW, most of the AR's I've shot chew jacketed bullets up pretty good, too.

Here we go again. Im giving my opinion, ive seen cast jam up a semi faster than a cheetah on cocaine. I dont deal with lead in gas guns either because of gas issues.

I've seen all kinds of things. That doesn't mean that my observations make for universal truths. Just as often I've seen the exact opposite occur as well. Which is right? If it's your opinion state such rather than asserting it as fact. Just my opinion.

May I step in?
I've been reloading and casting for 7.62x39mm for a little while. The only place I find leading is in the gas tube, which is bad enough, but removing chambered rounds occasionally reveals no bullet deformation I can remember seeing. Rifle used is an SA vz-58 from CzechpointUSA. I also shoot jacketed, plated and cast in this caliber out of a CZ 527M bolt action rifle with good results. Best cast bullet so far seems to be the NOE 129 grain.
Strictly speaking of just cast bullets in any semi-auto, no, I have rarely seen any cast bullet loads jam up in any of my firearms. They get dirty fast, this is true, but when the revolver starts slowing down the mil-spec autos just keep on going.

Back to 7.62x39mm...slug the bore, but expect to use .311 - the .308 bores in 7.62x39mm are mostly in the old original Mini-Thirty rifles. Every 7.62x39mm bore I've owned works best with .311. Also, Berry's Manufacturing makes an excellent plated bullet in this caliber, a 125 grain .311 bullet. Works great in the 527M.

I have both small and large rifle primered 7.62x39mm brass, and the SRP are all older Remingtons. For 5.56mm I use the Remington 7.5 Small Rifle Bench Rest, and get excellent results. I;ve only been loading for this rifle for about a year, so we're still working on finding the perfect load, using H-335.

Not really. The 223/5.56 uses Small Rifle, the 7.62 x 39 uses Large Rifle except the older Rem brass used Small Rifle.

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sorry, i thought his primer question was referring to 223 vs. 5.56

excellent, thanks for the info