It keeps getting worse.
This was posted by a user of my Facebook page:
"I got the 556R with the intent of using the steel cased ammo. I took the rifle out today and it shot fine until I got to the wolf ammo. I called Sig and talked to Josh in customer service, he informed me that Sig will void the warranty if steel cased ammo is used and that it will not work in the rifle. Only brass and non-corrosive ammo is to be used in the rifle. i will be selling the rifle due to the fact that I have several cases of the steel ammo and that Sig did not put a disclaimer on the web. Josh made the statement " Its in the owner manual but not on the web" So if you are thinking of buying the Sig 556R you can only use brass ammo."
Another user on the sigarms556.com forums confirmed that customer service agents at Sig are now telling folks this on the phone, this time the caller spoke to a service rep named Scott:
OTOH as I was typing this I was on the phone with Sig and spoke with "Scott," and I asked him about this and was told it IS TRUE -- not supposed to be used with steel cased ammo!!
Not good considering steel cased ammo is the defacto standard in 7.62x39 and most people will shoot it. Not too many people will want to shoot $.90 a round ammo out of their rifle. I suspect most people want this rifle because of the cheap steel cased ammo and cheap AK mags.
But that's the other issue that's come to light. The 556R uses an alloy lower. Sig didn't reinforce the lower where the toe of the magazine locks in. If you use steel mags in the gun, you start to see serious erosion on the lower within as few as 1000 rounds. After a few thousand rounds fired out of steel mags there will be serious damage to the rifle. I fired 90 rounds out of a steel mag in my rifle and noticed the damage being done.