Interesting thread, hope I'm not hijacking anything here...
So, I bought some MFS .223 locally, and took it to an indoor range...sparks on the steel backstop. Not a shower like you get from steel core (that's like fireworks!), but some sparking nonetheless...like trying to start a campfire with one of those magnesium sticks, or a torch-lighting striker.
Another shooter and I dissected one and it is definitely lead core (I could carve the core with my thumbnail), with what looked like copper on the outside. Didn't see anything hard & shiny like steel anywhere, but it held to a magnet. The case is steel (no problems with operation, the gun worked flawlessly with this ammo), so we figured maybe it was a bimetallic bullet jacket...?? The box read 'Germany' (black box of 20 rds, wrapped in paper inside) but it was advertised as Hungarian...so likely an Umbrella Company, as was mentioned earlier.
Our range has a 'no steel core' rule, like most indoor ranges (from what I've read/heard), but steel jacketed isn't outlawed still, it didn't seem 'right,' so I think I'll save this for the outdoor range (nothing to catch fire).
Thanks the extent of my experience with this stuff. If anyone can provide some additional information/experience, that would be helpful.
Here's some pics:
Ps: the squishy one resulted from clipping the point and finding nothing but copper-looking material, and then a subsequent pinch midway on the bullet, caused the lead to squish out like toothpaste.
