RCBS Formula 1 Brass Cleaning Media Walnut Hull - 5 lb

Keeping brass clean is one of those reloading tasks that feels tedious until you realize how much it affects your consistency and component life. The RCBS Formula 1 Brass Cleaning Media Walnut Hull is walnut-based media ground to 12-12 sieve size, designed to cut through the carbon, corrosion, and crud that accumulates on fired cases. This 5 lb bag works in any vibratory tumbler—whether you're running an RCBS Sidewinder rotary case tumbler or another brand's standard vibratory unit—making it a straightforward upgrade to your case prep routine without requiring new equipment.

Walnut hull media is the workhorse of brass cleaning. It's aggressive enough to handle seriously dirty brass, stripping away the buildup that can affect accurate case measurements and die performance, yet it won't damage case integrity the way overly coarse media can. At 12-12 sieve size, Formula 1 strikes that practical balance: you'll see noticeable results in a reasonable cycle time, and your cases will come out genuinely clean rather than just cosmetically polished.

The 5 lb volume gives you enough media for multiple cleaning runs before you need to refresh it. If you want to take brass finish a step further after Formula 1 does the heavy lifting, RCBS also offers Formula 2 (ground corn cob) as a final polish stage—but Formula 1 is built to get the job done on its own for most reloaders who prioritize cleanliness over show-room shine.

Key Features

• Walnut hull media cuts through carbon and corrosion on fired brass
• Ground to 12-12 sieve size for effective cleaning in one cycle
• Compatible with any vibratory tumbler, including RCBS Sidewinder rotary tumblers
• 5 lb bag provides multiple uses before media replacement needed
• Ready to use—no mixing or prep required

Specifications

Frequently Asked Questions

Will Formula 1 work in my vibratory tumbler?

Yes. RCBS Formula 1 walnut hull media is compatible with any standard vibratory tumbler, as well as the RCBS Sidewinder rotary case tumbler. No special equipment is required.

How dirty can brass be before Formula 1 won't clean it?

Formula 1 is formulated to handle seriously soiled cases. The 12-12 sieve size walnut hull is aggressive enough to cut through carbon, corrosion, and fired debris. If brass is heavily corroded or has been stored wet, Formula 1 will make a significant difference; extremely stubborn cases may benefit from a longer cycle time.

Can I use Formula 1 as a final polish, or should I follow up with another media?

Formula 1 is designed to clean thoroughly and will leave brass in good condition for reloading. If you want a higher luster finish for display or resale, RCBS offers Formula 2 (ground corn cob) as an optional final polish stage, but it is not required for function.

How long does the 5 lb bag last?

That depends on how often you tumble and how much brass per cycle, but 5 lbs is a substantial quantity that will support many cleaning runs before the media becomes saturated and requires replacement.