Test Subject: 55gr .223 Remington FMJ
Target Medium: CRS High Density Vulcanized Ballistic Rubber
Introduction & Executive Summary
In the CRS live-fire test described here, twelve 12″ × 12″ × 1″ high-density ballistic rubber panels were stacked to create a 12-inch target. The panels contained no embedded metal screen. A 55-grain .223 Remington FMJ round was reported to stop at a depth of approximately 6 inches. The stated 3,200 ft/s is a nominal muzzle velocity, not a documented measurement of velocity at impact. This stopping depth applies to this test setup, not every .223 round or rubber installation.
This article explains the observed penetration result and discusses how thickness and construction can affect projectile capture. Evidence note: the numerical breakdowns below are illustrative, unvalidated estimates—not chronograph measurements inside each panel. The observed stopping depth alone does not establish intermediate velocities, a universal stopping thickness or the performance of a solid block.
1. Velocity & Energy Dissipation Across the Stacked Panels
A bullet should not be assumed to lose equal speed per inch of rubber. Resistance can depend on material deformation, projectile condition and orientation, and the assembly. The stopping-depth observation does not identify a unique deceleration curve or establish that quadratic drag alone governs this test.
For illustration, assuming roughly equal energy loss over successive layers produces unequal velocity losses. That assumption is not a measured result of this test and should not be confused with a validated quadratic-drag model.
Illustrative Panel-by-Panel Breakdown (Not Measured)
| Panel # | Depth Traversed | Entry Velocity | Velocity Dropped | Retained Energy | Kinetic Energy Lost |
|---|---|---|---|---|---|
| Panel 1 | 0″ to 1″ | 3,200 ft/s | 291 ft/s (9.1%) | 1,032 ft-lbs (82.5%) | 219 ft-lbs |
| Panel 2 | 1″ to 2″ | 2,909 ft/s | 299 ft/s (9.3%) | 831 ft-lbs (66.4%) | 201 ft-lbs |
| Panel 3 | 2″ to 3″ | 2,610 ft/s | 348 ft/s (10.9%) | 631 ft-lbs (50.4%) | 200 ft-lbs |
| Panel 4 | 3″ to 4″ | 2,262 ft/s | 414 ft/s (12.9%) | 430 ft-lbs (34.4%) | 201 ft-lbs |
| Panel 5 | 4″ to 5″ | 1,848 ft/s | 541 ft/s (16.9%) | 215 ft-lbs (17.2%) | 215 ft-lbs |
| Panel 6 | 5″ to 6″ | 1,307 ft/s | 1,307 ft/s (40.9%) | 0 ft-lbs (0.0%) | 215 ft-lbs |
The intermediate speeds and energies in this table illustrate an assumed energy-loss pattern. They were not measured panel by panel and are not suitable for specifying a backstop, predicting an exit velocity or establishing a protection rating.
2. Solid Block vs. Layered Panels: The Gap Effect
Layered panels and solid rubber blocks may behave differently, but this stacked-panel test did not include a documented matched comparison with a solid block. A 20% solid-block advantage was not established by this test.
The approximately 6-inch stopping depth is the reported observation for the screen-free stack. The previously suggested 4.8-inch solid-block depth is an unverified extrapolation, not an observed result.
Observed: screen-free stacked panels, approximately 6-inch stopping depth. Not established: stopping depth in an equivalent solid block.
What Could Differ Between Solid and Layered Rubber?
- Layer interfaces: Gaps and contact between panels may affect deformation and the projectile path. Their effect was not isolated or measured in this test.
- Support and flexing: Panel restraint and backing can change how the rubber deforms. A matched comparison is needed to determine whether a particular solid or layered arrangement performs better.
- Projectile behavior: Changes in orientation or deformation can affect penetration. No internal imaging or other evidence supplied with this test establishes where or whether yaw or fragmentation occurred.
3. Illustrative Speeds Through Solid Rubber Panels
The following figures are retained as unvalidated illustrative estimates from the earlier analysis. They are not exact predictions or measured results for standalone panels. The unverified solid-block adjustment means these figures must not be used for range design or ammunition approval.
Illustrative Exit Velocities — Not Validated Test Data
- 1.0-Inch Solid Rubber Panel:
- Entry: 3,200 ft/s | Exit: 2,848 ft/s
- Drop: 352 ft/s (11% reduction)
- Energy Retained: 79.2% (991 ft-lbs remaining)
- 1.5-Inch Solid Rubber Panel:
- Entry: 3,200 ft/s | Exit: 2,654 ft/s
- Drop: 546 ft/s (17% reduction)
- Energy Retained: 68.7% (859 ft-lbs remaining)
- 2.0-Inch Solid Rubber Panel:
- Entry: 3,200 ft/s | Exit: 2,443 ft/s
- Drop: 757 ft/s (24% reduction)
- Energy Retained: 58.3% (729 ft-lbs remaining)
4. Key Takeaways
- Observed capture: The .223 round was reported to stop at approximately 6 inches in the tested screen-free stack. Intermediate speeds were not measured.
- Construction matters: This test does not establish a percentage advantage for solid blocks, screened Titan products or other configurations.
- Evaluate the complete range: Rubber is intended to help mitigate ricochet and manage impact; projectile capture is an additional, configuration-dependent capability. Forward penetration through a rubber component is not by itself a failure of its assigned role, but the full range system must provide appropriate containment.
Application limits: Ammunition, impact velocity, distance, angle, shot distribution, accumulated wear, rubber thickness and backing all matter. This stopping-depth test does not establish ricochet performance, an NIJ rating, steel service life or a universal caliber rating. Separate July 2021 customer tests used different standard and screened Titan panel assemblies and recorded forward exits; those results should not be treated as validation of the estimates above.
Earlier companion PDF: illustrative analysis. This legacy file may retain the original modeling claims; it is not a validated test report. Read it with the limitations stated in this article.
For separate measured panel results and block-test photographs, read CRS ballistic rubber customer testing: panels, Titan blocks and range safety. The different configurations are documented separately.
