5.56 pressure vs .223 pressure

[blacksmithden]

This guy does a little experimenting to see if one really does have more jam than the other.

[Gaidheal]

Both fed through my Galil SARs, 30 at a time, back when Canada was a place I liked

BTW - the muzzle flash was something to see (with either) from the 13" barrel on the SAR... Shooting prone required pretty serious debris clearing first.

[SwissArmyMan]

I've shoot 500 rds of each. Didn't notice anything, didn't affect my sights at 100 yds. No problems with extraction. Maybe the cases kicked a bit further but who cares??

I didn't use a chronograph so not a scientific observation. If someone get me one, I'd gladly give a scientific review.

[Gaidheal]

.308 & 7.62 NATO both fed through my FN L1A1 just fine too, albeit at 20 rounds per dump

Another note on the Galils - they dented the cases on eject... never had a jam but the cases were use-once. LOL They regularly flew several bays over at the range - I often shot at the far-right so no one else got hit with hot dented brass. LMAO

[SwissArmyMan]

Don't feel bad, a T97 will kick cases straight to China.

[Grimlock]

Mouth breathers will still say your rifle will blow up, you will get fingernail cancer and your dick will fall off if you use 556 in a 223. The absence of exploded rifles is negative proof.

[Lee Enfield]

I have used both, never really noticed any difference.

[harbl_the_cat]

5.56mm cases are often slightly longer than .223. Most of the 5.56mm cases I find are at or over 1.760 by about 0.01" or so, most .223 are under.

Interestingly, I loaded a batch of a few hundred .223 / 5.56mm cases trimmed to under 1.750 and didn't realize until a year later I was 1gn over the do not exceed data listed in my Lee Reloaders manual.

The result: about 2MOA accuracy with about 300 rounds fired through my MVP and American Predator.

I'm going back to work up a proper load and get proper data - but I think the big difference is with the longer case length, there's the potential for the case neck to be pinched when it's chambered in some guns, which would cause enough of a pressure spike to ruin accuracy (I think this is why Norinco .223 surplus is very inaccurate - it's both hot and the cases tend to be at or slightly longer than 1.760.)

Conversely, with a shorter case length, there's the potential that the bullet won't engage the rifling consistently if chambered in a 5.56, which may result in poorer accuracy.

Unless you do a double charge or have a squib, I don't think you're going to KB anything, and given that 5.56 and .223 are so similar minus case lengths, I think the only thing you MAY experience mixing ammo/guns is potentially poorer accuracy.

[Grimlock]

I have a .223 bolt action that is more accurate with 5.56 ball than .223. I also own a case trimmer.

[Greglc]

Can we move on to 7.62x51 and 308, I still have about 450 of 7.62x51, stupidly sold the m305 just before ban. But looking online looks like it's ok in 308, any comments?