Railcar, a dishwasher?
I've used a dishwasher on paintball gun parts and my old AMT Back-Up.
The dishwasher and normal dishwasher soap are tough on anodizing and plastic parts, but my only aluminum marker is a milsim (Tippman A5) and a rough patina on my vintage hopper looks good with the worn brassbrown finish of my only hopper fed Sheridan pump.
I might have run that marker through the dishwasher accidently once. No harm.
My AMT showed rust spots on its non stainless parts immediately, so I stopped that for all non stainless gun parts.
I use my dishwasher for anything from watches to Hot Wheels to litter boxes , though I might run it empty a few times after washing something nasty