As above, for me the top executors of this style are Keith Brewer and Hal Hutchinson but releases I usually reach for when in the mood...
Grunt - Seer of Decay disc 2
An early taste of Finnish steel and possibly the first full scrap metal release I heard which triggered a love for this style and naturally lead to discovering a bunch of other Finns.
Jaakko Vanhala - Feral Earth
Mindblowingly detailed stuff.
Bizarre Uproar - Fifteen Years Of "Filth & Violence" - Metal
Gotta have some BU in here, don't recall what has the most raw metal material but his scrap loops era is gold.
V/A - Sonno Ferrum
Killer Finnish comp where you're forced to blindly pick out each artists approach to the source as tracks are (deliberately) left uncredited.
Hal Hutchinson - ANY
Hal's factory of metal sound technique is unmatched!
Orgasmic Response Unit - Lesbian Hospital Orgasmic Response Unit
Just two tapes of solid metal worship.
Also Pussyfooter, first Aprapat tape, The New Boyfriends...