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Hammer Spawn specs
The Hammer Spawn is a solid reactive ball with the Gauntlet core. Here are its published specs, how they compare with the other current balls in our table, and what the numbers mean on the lane.
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| Coverstock | HK22C² Solid |
|---|---|
| Cover type | Solid reactive |
| Core (weight block) | Gauntlet |
| Core type | Asymmetric |
| RG | 2.501 |
| Differential | 0.050 |
| Mass bias / intermediate diff. | 0.012 |
| Factory finish | 500, 1000 Siaair Micro Pad |
| Maker's category | High Performance |
| Color | Black |
| Weights | 16-12 Pounds |
| Release date (maker) | May 14, 2026 |
| USBC approved | 5 May 2026 |
Numbers as Hammer publishes them, checked 21 October 2026. Published for a 15-pound ball. Drilling changes how a ball behaves, so a pro shop's layout matters as much as these numbers.
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What the numbers mean
RG 2.501. That is lower than 42% of the 134 current reactive and urethane balls in our table, so it sits on the high side. Storm says "a high RG ball delays its revving, offering more length and angular motion down the lane."
Differential 0.050. Higher than 57% of the balls in our table. Storm says "a high differential ball will create a sharper angle of entry into the pins."
Solid reactive cover. Storm says solid covers are "particularly effective on fresh oil patterns," and bowling.com calls them best on heavier oil.
Asymmetric core. Storm says asymmetric balls have "varying RG values along different axes" and more angular motion.
USBC allows an RG from 2.447 to 2.813 inches and a differential of at most 0.060 inches (Equipment Specifications Manual, March 2026). Our ball spec table lists every current ball we track, and who makes bowling balls covers which company owns Hammer.
Balls with similar numbers
Same cover type, closest RG and differential in our table:
- Roto Grip Transformer: RG 2.500, differential 0.050
- 900 Global Viking Conquest: RG 2.500, differential 0.050
- Brunswick Combat Solid: RG 2.502, differential 0.051
- Radical Outer Limits Black Hole: RG 2.499, differential 0.051
Sources: Hammer product page; Storm, "Inside The Bowling Ball"; Storm, "The Coverstock"; bowling.com coverstock FAQ; USBC Approved Ball List (20 October 2026); USBC Equipment Specifications Manual.