Need some help...

These are some wolf spent casings that kept jamming (FTE).  Noticed something on the cases, not sure what exactly it is.
Believe this caused the rim to rip off too.

thanks!

Looks like powder residue/blow-by from the cases not fully sealing to the cha,ber walls when fired.

It is one theory that the steel cases don't expand as fully and snap back to original shape earlier in the pressure drop than brass cases.  This is thought to be a contributing factor to why steel cased ammo seems very dirty, and why shooting brass cased ammo after steel cased ammo can result in stuck cases.  There is usially more build-up of fouling in the chamber after a heavy diet of steel cased ammo, and it may require more frequent scrubbing with a chamber brush.

That is carbon that is blown back because steel doesn't swell up like brass.
Shoot a box or so of wolf and then shoot a brass cased round, look at all the crud stuck to the side of the brass.

Those specs on the shells are a warning sign saying "clean yer damn chamber".