Thread: 5.56/.223?

I have a New England Handi-rifle in .223. Is it "safe" to shoot 5.56 through this rifle?

The experts will chime in but the 5.56 cases are a little thicker and will produce higher pressures in the chamber if it's a 223 chamber.
So you have to decide if the gun is heavy enough to handle the pressure difference.
Not sure I would on a New England and you can get 223 for about the same cost.

I only ask because I have 5.56 ammo.

The 5.56mm are also slightly longer. You can shoot .223 in a 5.56 chamber but not the other way around.

Not a good idea. Higher pressure, not safe overall.

The answer is NO.

Burrowed from The Gun Zone -- SAAMI on 5.56 v. .223 Remington

The .223 Remington is rated for a maximum of 50,000 CUP while the 5.56mm is rated for 60,000 CUP. That extra 10,000 CUP is likely sufficient to cause a failure in a chamber that's only rated for the "sporting" .223 Remington.

The .223 Remington and the 5.56mm NATO, when checked with a chamber ream from a reliable manufacturer of each, also have discernable differences in the areas of freebore diameter, freebore length (leade) and angle of the throat.

Originally Posted by Lasers

Burrowed from The Gun Zone -- SAAMI on 5.56 v. .223 Remington

The .223 Remington is rated for a maximum of 50,000 CUP while the 5.56mm is rated for 60,000 CUP. That extra 10,000 CUP is likely sufficient to cause a failure in a chamber that's only rated for the "sporting" .223 Remington.

The .223 Remington and the 5.56mm NATO, when checked with a chamber ream from a reliable manufacturer of each, also have discernable differences in the areas of freebore diameter, freebore length (leade) and angle of the throat.

I have been overloading handloads as a hobby to get to the truth, ever since I made my money overloading other military equipment to get to the truth.

See these pics of 223 brass? It was at much higher than 5.56 specs.

If you could just point me to that sporting 223 that is likely to blow up, I will very soon buy one and test it.

I did get a Lux 222 that is just a converted 22LR with the only locking is the tiny bolt handle in a slot in the tube receiver... but alas, I can't seem to blow it up.

The handi rifle has one of the thickest chambers for 223 around...I would not suggest shooting 5.56 on regular basis but it can be done thru your single shot safely it will just wear quicker...Also if you reload back off by at least 4 to5 grains when loading a 5.56 case versus 223 case. I get about the same fps out of both when I load the 5.56 about 7 grains less tha the 223

I have calculated the strength of my 45/70 handi rifle back in 1999 with the help of my gun designer chief engineer father and mechanical engineering professor.

I had never heard of double shear, section modulus, and Lame's thick wall tube stress formula before then. I calculated it was much stronger that the brass could ever take.

Some doubted my math, so I validated it with testing.

A test from 1999

45/70 work up with; 405 gr cast with lube bands, CCI 200 primers, Win
brass, old Unique [dirty] powder, chamber well lubricated between
firings with CLP for max bolt thrust.

Quickload calculation of pressure and velocity with 405 gr, Unique

shot 0) 15 gr, 24,700 psi, 1271 fps, no shot fired, listed for Quickload reference point only
shot 1) 18 gr, 33,217psi, 1403 fps, primer looks fine.
shot 2) 20 gr, 39,435 psi, 1485 fps, primer is fine
shot 3) 22 gr, 46,133 psi, 1563 fps, primer looks flat.
shot 4) 24 gr, 53,334 psi, 1637 fps, primer is flat.
shot 5) 26 gr, 61,067 psi, 1709 fps, primer is top hat and flowing,
action popped open and case ejected on firing
shot 6) 28 gr, 69,366 psi, 1778 fps, primer is top hat and flowing, case
head expansion .001", action popped open and case ejected on firing
shot 7) 30 gr, 78275 psi, 1846 fsp, case head expansion .0015" action
popped open and case ejected on firing, some leading in the muzzle.
shot 8) 32 gr, 87,841 psi, 1911 fps, case head expansion .0025", case head separating where case head is flowing into the extractor, action popped open, some leading in the muzzle, and case ejected on firing, primer is spreading out .010"

There was no change in headspace, but I had to stop the work up because of case head separation where the case head flowed into the extractor.

Reference loads:

1) "Loads for the 45/70" from the H.P.White laboratory via "American
Rifleman" 1950~1968 via "NRA Handloader's Guide" 1969 says:
405 gr Rem S.P., 17.5 gr Unique, 1286 fps, 25,240 pounds pressure, for 1886 Win

2) "Lyman's 47th" 1992 says:
400 gr cast, 16.5 gr Unique, 1286 fps, 27,000 cup, for 1886 Win

3) "Lyman's 47th" 1992 says:
385 cast gr cast, 17.5 gr Unique, 1411 fps, 38,500 cup, for Ruger #1

Not real sure what the 45-70 info does for the 223/5.56 discussion,but I'm not a mechanical engineer

Here is how thin walled hoop stress works.
The stress on the steel is
Stress = [Pressure] [Inside diameter]/ 2[wall thickness]

That formula is obvious upon inspection to bright jr high kids.
Lame's formula for thick wall was figured out 500 years ago, by Lame, the French Mathematician, and I would have never figured that out on my own.
But the answers for the two systems are always close, so intuitively, just visualize the thin wall formula.

The stress is proportional to the inside diameter.
So the barrel bursting stress gets worse as the inside diameter gets bigger or as the chamber walls get thinner.
That is why Elmer Keith blew up so many SAA 45 Colts, until he overloaded the 44 special revolvers that both the thicker walls and smaller chamber diameters, and he was able to make the 44 mag pressures.

That is why the 45/70 is so much harder of a test for the handi rifle than the .223... to take the rifle to brass failure
Hoop stress is higher.
The bolt thrust is higher.

The Ruger Mini-14 Target Rifle has a caution to never shoot 5.56 in it according to one report I read on the .223/5.56 dangers.

I know as a rule, you should never run 5.56 in a rifle chambered in .223. "BUT" the Handi-Rifle is a pretty tough gun.

Originally Posted by Izzy

I know as a rule, you should never run 5.56 in a rifle chambered in .223. "BUT" the Handi-Rifle is a pretty tough gun.

I still wouldn't do it unless it was a life or death situation and just because the OP happens to already have some 5.56 isn't reason enough for me to try it.