Is a true Swiss 14.3 barrel from a SIG 551-2 rated for 556?

TIA

Yes it is. Swiss DoD / Nato specs for 5.56 rifle ammo are in accordance with CIP which does not differentiate between .223 Rem and 5.56x45. This whole .223 vs 5.56 confusion is a US problem which is not known in Europe and CIP membership countries. I recommend a visit of the CIP homepage if you are in doubt.

quote:

Originally posted by sf192nd:
Is a true Swiss 14.3 barrel from a SIG 551-2 rated for 556?

TIA

I'm not clear on what you mean by "rated". If you mean caliber wise, as OTD posted, then the answer is yes. HOWEVER, if you are looking to swap barrels the thread pitch should be different between the two platforms.