Understanding the Test Results

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Understanding the test results:

Testing bullets in ballistic gelatin can sometimes be a complicated business, depending upon what sorts of performance criteria one is trying to measure. Below is an actual data sheet from a previous test, with an explanation as to what all of the terms mean. For further information, please don’t hesitate to email us at Brassfetcher@Brassfetcher.com.

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Brass Fetcher Ballistic Testing

Test # 380ACP 1
Bare gelatin block. (Nominal 10% concentration) – What barriers were placed in front of the gelatin block, if any, and what concentration of gelatin block was used. The higher the number, the more resistant the block to bullet penetration. 10% blocks are typically associated with the FBI, as their standard concentration for bullet testing.

Cartridge : .380ACP Remington 102gr Golden Saber JHP

Block Calibration : 3.1 ± 0.05 inch penetration @ 576 ± 0.5 ft/sec – How does the viscosity of the tested block compare to the ‘perfect’ gelatin block? An acceptable 10% block is generally considered to allow for a standard airgun BB, impacting the block at 590 ft/sec to penetrate to 3.4” in the block. There are allowances for variation in velocity and penetration such that the BB can impact anywhere from 575 ft/sec to 605 ft/sec and penetrate anywhere from 2.9” to 3.7” in the gelatin block. The calibration is an indication of how closely a gelatin block approximates penetration depth in muscle tissue.

Block Calibration temperature : 37.1 ± 0.05 Degrees Fahrenheit – Temperature of the penetration track of the calibration BB, taken immediately after depth measurements are made. The ‘perfect’ block is 39.0 degrees Fahrenheit, but a block is generally considered to be acceptable to most in the industry if it is at a temperature of 29 to 49 degrees Fahrenheit. The colder a gelatin block is, the more resistant to bullet penetration it is.

Block Core temperature : NR – Temperature of the geometric center of the gelatin block, taken immediately after shot impact and photographing of the block. Gives an indication of the temperature of the gelatin that was shot by the bullet during penetration.

Bullet Performance:

Impact Velocity : 765 ± 0.5 feet/second – Velocity of the bullet measured at 2 feet distance from the impact face of the gelatin block. The bullet may have impacted 1-2 ft/sec slower than the velocity measurement.

Deepest Penetration Depth : 9.5 ± 0.05 Inch – The straight-line distance from the impact face of the gelatin block to the deepest bullet/bullet fragment or crack occurring as a result of the bullet penetration.

Maximum Crack Diameter : 1.4 ± 0.05 Inch – The furthest distance, measured perpendicular to the bullets trajectory, of any crack occurring as a result of bullet penetration.

Max Crack Diameter Location : 1.6 ± 0.05 Inch – The straight-line distance from the impact face of the gelatin block to the location of the maximum crack diameter.

Cavitation Depth : NR – The depth at which the cracking in the gelatin stops being greater in diameter than the track that is being pushed by the bullet.

Notes:
Weapon – Kel-Tec P3AT, with 2.75” barrel length
Distance – 10.0 feet, muzzle to gelatin impact face
Test site conditions - 40 deg F
Time out of refrigeration prior to shot impact - 4 minutes
Bullet recovered weight – 101.5 ± 0.05gr
Bullet recovered average diameter - 0.521 ± 0.0005"
Bullet recovered length - 0.390 ± 0.0005"

Note : the ‘ ± ’ sign is used to indicate the magnitude of the uncertainty of the measurement. All measuring devices have an inherent uncertainty. Unless specified by the equipment manufacturer, the uncertainty can be considered to be one-half of the lowest decimal place that the device can measure to. A penetration measurement of (say) 13.0 inches with an uncertainty of (say) ± 0.05 inches means that the bullet could have actually penetrated as little as 12.95 inches or as deep as 13.05 inches. This is probably not significant. If the penetration measurement was (say) 13.0 inches with an uncertainty of (say) ± 0.25 inches, this means that the bullet could have actually penetrated as little as 12.75 inches or as deep as 13.25 inches. In the second case, the uncertainty of the measurement is very significant.