5.56 in a .223 Winchester

I just put some mil 5.56 rounds through my .223 Winchester and each one tumbled so that they hit the target side on. I know that the shoulders of the chamber are a different shape but would this distort the round sufficiently so that it's tumbling as soon as it leaves the rifle?
I remember that this sometimes happened with the Armalite but back then we were always told that this round was designed to be highly unstable. Seems that I can't save money using surplus ammunition.
Anyone use military 5.56 in a civvy rifle?
wikipedia said:
Using commercial .223 Remington cartridges in a 5.56mm NATO chambered rifle should work reliably, but generally will not be as accurate as when fired from a .223 Remington chambered gun due to the longer leade. Using 5.56mm 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 the SAAMI recommends against the practice...
Link. 5.56mm NATO ball weighs in at 62gr; have you considered the difference between that and the commercial ammunition you might purchase, as that'll have an effect on the ballistics?
Beerhunter said:
acornminiminor said:
we were always told that this round was designed to be highly unstable.
But not in the air, only when it hits something more substantial than a paper target.
It was in the ulu where one tended to strip the leaves off the trees before hitting the target - or not.

Thanks for the suggestions, I thought that my rifle was a 1 in 8 which should be the right twist but it turns out to be a 1:14. So back to commercial at over a pound a round.


The shoulders arent different, the differences tend to be in whats accepted under STANAG and the cross in a circle stamp and what is commercially or handload available and how you have your rounds seated, longer leade etc. All of this affects pressure and accuraccy but in your case I would suggest that 69 grain or heavier is unsuitable in anything less than 1 in 9. I use a 1 in 12 Ruger and am happy with 55 grain loads out to 300 yards.
All ammo can be unsafe even factory if its stored or handled incorrectly, most will be fine. Remember dont believe everything Wiki says and SAAMI exists to protect US gun and ammo companies in a litigious environment.
Hi Acornminiminor
Weve got a couple of slower twist .223/5.56 barrel rifles in my club. 1 in 12 and 1in 14 The owners are useing Barnuad (Russian steel cased 55 grain) which performs quite well and at £20-£25 a 100 is not bad.It may be worth a try.

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