Bowling ball core · Hammer
Hammer FAB Asymmetric
Asymmetric Hammer core
An asymmetric core with later rev-up, more length and medium flare, built for dry to medium oil. 1 of the 3 balls with this core are in stock at BowlersMart.
- Asymmetric
- RG 2.550
- Diff 0.051
- MB 0.014

Specs
RG AT 15 LB
2.550
Later rev-up, more length
87% of the reactive and urethane balls we stock have a lower RG.
DIFFERENTIAL AT 15 LB
0.051
Medium flare
65% of the reactive and urethane balls we stock have a lower differential.
MASS BIAS AT 15 LB
0.014
Mild asymmetry
16% of the asymmetric reactive and urethane balls we stock have a lower mass bias.
| Weight | RG | DifferentialDiff | Mass biasMB |
|---|---|---|---|
| 16 lb | 2.530 | 0.051 | 0.014 |
| 15 lbUsed on this page | 2.550 | 0.051 | 0.014 |
| 14 lb | 2.620 | 0.045 | 0.014 |
| 13 lb | 2.580 | 0.043 | Not listed |
Source: Hammer published specs, as shown on BowlersMart’s original Hammer FAB Asymmetric core page (2022). RG and differential change with ball weight; use the row for the weight you throw. The highlighted 15 lb row is the one used on this page.
Balls with the Hammer FAB Asymmetric
1 of the 3 balls with the Hammer FAB Asymmetric are in stock at BowlersMart. Same core, different covers: pick the cover for the lanes you bowl on.

Show 2 balls no longer available at BowlersMart
| Ball | Cover | First seen |
|---|---|---|
| Hammer Purple Solid Urethane Overseas Bowling Ball | Hammer Solid Urethane | June 2024 |
| Hammer Purple Solid Urethane Overseas 2ND QUALITY Bowling Ball | Hammer Solid Urethane | April 2026 |
Where the Hammer FAB Asymmetric sits
Each dot is a core in balls we stock. Cores close together roll alike; the cover and layout decide the rest.
Navy ring = a ball in your bag. Dashed ring = off this chart, or this same core.
Nearest cores, zoomed in
Navy ring = a ball in your bag. Dashed ring = off this chart, or this same core.
This core 1 Nearest cores Other cores
| Core | Brand | Shape | RG | Diff | vs this core |
|---|---|---|---|---|---|
|
|
Motiv | Symmetric | 2.550 | 0.050 | RG 0.000 · Diff −0.001 |
|
|
Storm | Asymmetric | 2.560 | 0.051 | RG +0.010 · Diff 0.000 |
|
|
Epic | Symmetric | 2.540 | 0.049 | RG −0.010 · Diff −0.002 |
|
|
Hammer | Symmetric | 2.560 | 0.049 | RG +0.010 · Diff −0.002 |
|
|
Hammer | Symmetric | 2.545 | 0.047 | RG −0.005 · Diff −0.004 |
|
|
Storm | Symmetric | 2.540 | 0.046 | RG −0.010 · Diff −0.005 |
Matches use 15 lb RG and differential.
Drilling and tools
FAB asymmetric core also provides incredible overall flair and hitting power.
Questions bowlers ask
What is the RG of the Hammer FAB Asymmetric?
At 15 lb the Hammer FAB Asymmetric has an RG of 2.550. It ranges from 2.530 to 2.620 across the listed weights.
What is the 14 lb RG of the Hammer FAB Asymmetric?
At 14 lb the RG is 2.620.
What is the differential of the Hammer FAB Asymmetric?
At 15 lb the differential is 0.051. The mass bias is 0.014.
Which bowling balls use the Hammer FAB Asymmetric?
Hammer Red Pearl Urethane Asym Overseas Bowling Ball, Hammer Purple Solid Urethane Overseas Bowling Ball, Hammer Purple Solid Urethane Overseas 2ND QUALITY Bowling Ball. 1 are in stock now.
How do the Hammer FAB Asymmetric specs change by weight?
At 16 lb: RG 2.530, differential 0.051, mass bias 0.014. The 12 lb values are not listed.
How does the Hammer FAB Asymmetric compare with my ball?
Type the ball you throw into the Compare with your ball box on this page. It shows the RG and differential side by side and saves your bag for every core page.
Sources and method
Specs. Hammer published specs, as shown on BowlersMart’s original Hammer FAB Asymmetric core page (2022), as published by the manufacturer.
Baseline. The baseline is 265 in-stock, published reactive and urethane balls. Plastic and polyester covers, 2-piece, 3-piece and pancake cores, missing covers and missing RG or differential values are excluded.
Percentiles. Percentiles are the share of baseline balls with a strictly lower or higher value; ties are not counted.
Nearest cores. Nearest cores are ranked by distance on standardized 15 lb RG and differential, with the same symmetric or asymmetric shape preferred among near ties (distance bands of 0.1).
Mass bias. Mass bias is compared among asymmetric balls with numeric mass bias only.
Updated. Catalog and page updated 2026-10-16.


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