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When a worn or undersized ball causes inconsistent shots, rattling assemblies, or premature wear in your equipment, the root issue is almost always material grade and dimensional accuracy. These 304 stainless steel ball bearings are sized from 10 mm (0.39 in) to 20 mm (0.79 in) and are designed for users who need repeatable performance — whether that's a hobbyist loading a slingshot or a technician replacing rolling elements in a light-duty bearing housing.
Each ball is machined from 304-grade austenitic stainless steel, offering a chromium-nickel alloy composition that resists surface oxidation in humid and mildly corrosive environments. Diameter options span 10 mm through 20 mm in 1 mm increments, and packs are available in 2, 5, or 10 pieces to match your project scale without over-ordering.
Typical applications include slingshot and wrist-rocket ammo where consistent mass and roundness affect trajectory, replacement rolling elements in drawer slides and light bearing races, marble-run and kinetic sculpture builds requiring uniform sphere diameter, and valve seat balls in low-pressure fluid systems where stainless compatibility is required.
| Material | 304 Stainless Steel (18-8 Chromium-Nickel Alloy) |
|---|---|
| Diameter Range | 10 mm – 20 mm (0.39 in – 0.79 in) |
| Diameter Increment | 1 mm steps (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 mm) |
| Diameter Tolerance | Typically ±0.05 mm |
| Surface Finish | Smooth machined sphere |
| Density | ~7.9 g/cm³ (typical for 304 SS) |
| Hardness | Typically HRC 25–35 (304 SS annealed) |
| Corrosion Resistance | Suitable for humid and mildly corrosive environments |
| Magnetic Properties | Largely non-magnetic (austenitic grade) |
| Pack Quantity Options | 2 pcs / 5 pcs / 10 pcs |
| Typical Applications | Slingshot ammo, light bearing replacement, valve seats, kinetic builds |
| Ball Size | See variant options |
| Package Quantity | See variant options |
Measure your slingshot pouch opening or the fork gap width. A ball that is too small will slip through; one that is too large will not seat properly and can affect accuracy. Most standard slingshot pouches accommodate balls in the 10–14 mm range, while heavier hunting-style slings often use 15–20 mm. When in doubt, order a 2-piece pack of two adjacent sizes to test fit before committing to a larger quantity.
304 stainless steel has a tensile strength of approximately 515 MPa and a hardness typically in the HRC 25–35 range. For recreational slingshot use at standard band tensions, this is sufficient. However, if you are using very high-draw-weight bands or competition-grade setups, consider hardened steel or chrome steel balls, which offer higher surface hardness and impact resistance.
304 stainless steel forms a passive chromium-oxide layer that resists rust in most outdoor and humid conditions. It is not fully immune — prolonged exposure to saltwater, chlorinated water, or strong acids can cause surface pitting over time. For marine or pool environments, 316 stainless steel offers better chloride resistance. For general outdoor use, 304 is a practical and cost-effective choice.
These balls are suitable for light-duty bearing replacement in applications such as drawer slides, lazy susans, and low-speed rotating assemblies. They are not precision-grade (ABEC/ISO rated) balls. If your application requires tight dimensional tolerances (Grade 10 or better), low noise, or high-speed rotation, please contact us to confirm suitability or browse our precision bearing listings.
304 stainless steel is widely used in low-pressure water, oil, and mild chemical valve applications. Verify that the ball diameter matches your valve seat bore — the typical tolerance for a good seal is ±0.02 mm or tighter. For high-pressure or aggressive chemical environments, consult your system specifications before use.
Weight depends on diameter. Using the density of 304 SS (~7.9 g/cm³), approximate weights are: 10 mm ≈ 4.1 g, 12 mm ≈ 7.1 g, 14 mm ≈ 11.3 g, 16 mm ≈ 16.9 g, 18 mm ≈ 24.1 g, 20 mm ≈ 33.0 g. Intermediate sizes fall proportionally between these values. These figures are calculated estimates; contact us if you need certified weight data for a specific size.
Both are austenitic stainless grades, but 316 adds molybdenum, which significantly improves resistance to chloride pitting and crevice corrosion. For most DIY, slingshot, and general mechanical uses, 304 provides adequate corrosion resistance at a lower cost. Choose 316 if your application involves saltwater, marine exposure, or chlorinated environments.
🛒 Select your Ball Size and Package Quantity above, then add to cart.
