Steel bore brushes - WWII surplus?

A few months ago I bought a box of military surplus .45 caliber brass bore brushes. There was a little over 1,000. In addition there was a couple hundred steel brushes. Identical, but in steel. I've been referring to them as stainless but I don't know this to be a fact. They almost look blued. I realize people generally don't want to use a steel brush but my question is, how did these come to be? Was it because brass was hard to get at some point? Or were they issued for a seperate reason?

Attachment 61757

Any part numbers or part of, on the brass shank?

Not a thing.

I think you'll find these are new production. I've been using exactly that pattern as of recent available from a local LEO supply company. Military brushes would be phosphor bronze or pig bristle, the latter being not so successful and the former being the standard for decades.

Agree with BAR that they are not WWII. Never heard of GI steel bristle .45 brushes, but I guess it could possibly be from a post Vietnam or later contract.

I have one military surplus .45 steel bristle bore brush. I believe it to be of Cold War, late 1970s to 80s manufacture as it was purchased in the mid-1990s from a gun show in an area populated by US defence facilities that sell off bulk lots of surplus equipment. That said, I can only guess that its anticipated use was for long-term storage, or for (armourer use) cleaning corroded .45 barrels.

Thanks for the info!