Corrosive Ammo. Clean firearms immediately!

[OCB]

Just piss in your barrel when you're done shooting.

Don't forget to take the bolt out first, though...ask me how I learned.

I've heard of M1 thumb, but never M1... Nevermind.

 

[Picton]

The British manufactured a specially designed funnel that fits precisely into the SMLE chamber solely so that soldiers could flush salts out of their barrels quickly. They issued those before WWI.

Over a hundred years on, and some haven’t gotten the word.

The water does the flushing. So any water-based liquid will work. It’s not rocket science, just field maintenance