Here is a link to a YouTube video that might shine some light on the seemingly never ending argument surrounding Bi-metal russian 223 ammo and premature barrel wear. In the video they actually test and determine the hardness of bi-metal bullets, standard copper clad lead and the hardness of a supposid Mil-spec AR-15 barrel.
https://www.youtube.com/watch?v=IWwmAMVh8Qs
I felt some who shoot a lot of the Russian 223 loaded with Bi-metal bullets or are considering it, might find it of value.
I did watch that video. Thanks for posting the link. 
That led to another video where a guy was using an electron microscope to see if the rifling actually cut through the thin outer part of the jacket material and was contacting the steel part of the jacket (and it was).
Watching the videos reminded me that the cheap, bi-metal ammo is a ‘hell no’ in any barrels of mine.
Watching the videos reminded me that the cheap, bi-metal ammo is a ‘hell no’ in any barrels of mine.
I know A LOT of guys who do shoot it, I like you will not. Back when 223 Wolf Gold was under $300/1k TYD I did take a bunch of steel cased 556 off a guys hands who bought it for use in his 223 bolt gun and most of the rounds wouldn’t chamber in his rifle. He didn’t know 556NATO and 223Rem are two different cartridges and I explained that they were and you can shoot 223 out of a 556 chamber and should avoid shooting 556 out of a 223 chamber. I did use a magnet to insure 100% it was loaded with lead core FMJ steel free projectiles. Even then I sold it to another guy at work for a fair price.
As I now have all the tools and parts I need to fix broken or malfunctioning extractors actually 3x more than # of bolts I own, I would if the price was cheap enough shoot steel cased 223 if it were loaded with a 100% lead core FMJ projectile, but prices being what they are and the fact I have a butt load of lead core FMJ bullets to reload on hand to ME live ammo loaded with steel core or bi-metal bullets are just not worth it at cheap prices and definitely NOT at current prices.
I don’t buy Russian steel jacket crap anymore either, although every time I think it’s gone, I find some more and fire it.
Now I don’t have much .308 and got some surplus 7.62x51 for my Armalite AR10’s.
Didn’t do much research when I bought it.
FNM (Portuguese) headstamp followed by xx-xx. I figure the first number is the year and second is the batch?
It is delinked, staked primers, and I assume Berdan primed. And magnetic. Oops.
I already fired a couple mags, worked fine.
Now I’m not sure I want to fire 40+ year old steel jacketed ammo through my DEF-10’s.
Best I can recall, a lot(maybe most) of the 1995-2005 era surplus 7.62×51 had copper plated steel jackets.
Mine is apparently from 1980. Attracts a magnet.
Yeah it was produced in the 70’s and 80’s. Surprised me, but Hirtenberger produced 7.62×51 that showed up surplus in the late 90’s was bimetal.
Not a common issue now, but some lots of Portuguese tended to have quite a few duds. Think 76-3 seems like a problematic lot #.
Mine was produce in the 70s, Thanks so much for producing the link .
Is the second number a batch number?
I.e. “80-35”
Are the XM-80 7.62 bullets bi-metal. I know they stick to a magnet. We don’t normally shoot junky ammo like that, but we’ve run a few boxes.
There’s a bunch of American made economy ammo using bimetal as well. WCC 94 M80 ball I shot stuck to a magnet as well as some Remington UMC .45 hardball I bought many years ago. The latter was a literal eye popper for the owner of one indoor range I used to shoot at who banned Russian bimetal but was selling the UMC for range fodder.
Swiss 7.5mm GP-11 for the K-31 is bi-metal using a mild steel jacket that is plated. I’ve never read any reports of premature bore wear or poor accuracy from that combo (rifle and ammo).
Perhaps the mild steel jacket isn’t as much of an issue if the plating metal alloy is of very high quality?
How thick is the Swiss plating? The entire jacket on a Gold Dot bullet is electroplated as I understand.
Good question, there’s probably someone who has measured the plating thickness but I don’t have an immediate answer.
One other factor is the quality and consistency of the mild steel jacket. I’m going to guess that’s an important component as well.