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5.56 / .223

Sabre industries .223 with a Remington match barrel is part of the latest toy collection, also with the TAC-SOL .22 bolt and barrel.

When I put regular .223 through it, it works a treat but that works out at about £30 per 100 shots.

If I put MOD 5.56 through it, it chambers and shoots fine but its an absolute nightmare re-cocking and extracting the spent case. Its as if its lodge firmly in the chamber.

I'm probably going to open myself to a barrage of abuse and its probably day one, week one stuff I'm being thick about but I was under the impression .22 /5.56 were the same....

Please correct me / make me feel stupid.


You're going to blow your face off.

Using 5.56x45mm NATO mil-spec cartridges (such as the M855) in a .223 Remington chambered rifle can lead to excessive wear and stress on the rifle and even be unsafe, and SAAMI recommends against the practice.

But hey...

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There's a very slight difference in the cartridge meaning you'll have extraction problems in a civvy weapon, but .223 will fire fine in military weapons. (As the chamber in a 5.56mm military weapon is slightly different to a civvy .223).


There are reams of internet pages about the differences or otherwise between the calibres. One of the complications being, besides case dimensions and capacities, the variances in datums for measuring headspace, etc. However, on balance, there should be no difference between the calibres in normal military and commercial loadings.

IIRC the usual problem with 5.56mm in a .223 is that the 5.56mm case is usually harder (if its military brass) and this leads to sticking and extraction problems......


Yeah, I always understood it as they're slightly different so you should use the one that the rifle was designed for where possible, but you can fire .223 through a 5.56 - but it's unwise to do it the other way around.

Talking out of my bum, via a mobile telephone.


5.56 NATO is designed for use in chambers that have a longer leade than .223, which was designed for use in bolt actions

Masses written on this, key risk that people stress over is that stuffing 5.56 into a .223 can spike pressures up, some reckon by as much as 15,000psi.

Mine has a .223 AR Match chamber and happily consumes 5.56
How many recorded instances of failure though? Not very many I'm guessing, without looking. If there were a serious issue there would be warnings on boxes.
For PGs info, I have used various brands of civvy .223 and RG .556 in my Mini 14, no problems, it eats anything and everything. The accuracy however is sh1t, but it's a fun gun. My Remington 700 will also eat most things, but because the barrel is a 1 in 12 twist it will not stabilise .556. However reloaded .556 cases with a 52 grn HPBT shoot very nicely. Having weighed a few cases both civvy and mil it would appear that .556 is always a bit heavier, due to thicker case walls. This is only a potential problem if you reload, there is less internal volume, therefore loads should be reduced.


And yet folk don't bat an eyelid at the tolerance variations in .303 or 7.62 x 64R they just get on with it! One day in the future it will all be normal to get chambers measured to see if they correspond to stanag!
theoretical problem. Am unaware of it ever really being an issue.

Doesn't stop armchair ballisticians aching their balls over it on the Intertubes.

If it was a genuine problem, in the über-litigious US all boxes of surplus M855 would be marked with "WARNING NOT TO BE USED IN .223 REMINGTON CHAMBERS". A box of 5.56 is more likely to contain a warning about possibly containing nuts. Ergo, it's not a problem.

And yes, I've fired 5.6mm GP90 in my .223. And 62gn Prvi .223. And Nato-marked RUAG. And S&B which is marked ".223 Rem / 5.56 M193".
Tried again this afternoon and its a struggle and no pleasure to recock, almost impossible with the toggle without the extension to the charging handle.

No pleasure in it at all, so its back to paying for ammo!!
If some civvy chambered to .223 has no problems, why not change you weapon?

It's as good a reason as any and will save you money on ammo in the long run.
When you buy your ammo do you buy it from the UK only?

It might be worth looking further afield within the EU.


The answer to all your problems, infestation, marital or familial is 7.62 Full Metal Jacket.

Thank you. I'm here until the Mods ROP me.


If I had a guaranteed source of surplus I'd have the chamber polished/reamed. Otherwise learn to reload and develop a load your bundook gets on with!

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