You can check for a bimetal jacket with a magnet. Like the Greek ammo that CMP sells, there is a notation on their website that says "This ammunition attracts a magnet" or something similar.
This is due to some (several) ranges/locales not allowing bimetal projectiles due the risk of starting a fire/wildfire caused by bullets creating a spark on impact with rocks ect.
A lot of 7.62x51 Nato ammunition is bimetal. A lot of US .30-06 M2 Ball and AP ammunition was/is bimetal. I have some bimetal WWI .30-06 ammo. Pre-M2 Ball.
I shoot a lot of steel cased .223 with few problems. I have stuck a brass cased cartridge in the chamber a few times because I didn't clean the chamber after shooting a bunch of steel cased ammo. It takes quite a bit of steel cased ammo to foul a chamber to the point that I've had problems chambering/extracting brass cased ammo. This is with .556 chambers.
Most of the cheap steel cased ammo is dirty. Real dirty. I compare it to Remington bulk pack .22 LR. Cheap, dirty burning ammo.
The rifle wasn't designed to run steel. It's like putting E85 in your non E85 car and getting mad when it doesn't run right.
I do not shoot steel, and i would NEVER recommend shooting steel cased ammo.