After more than 400 additional test rounds, it was determined that beanbags with an impact surface area of less than 1.3 square inches penetrate tissue, causing a significant risk of serious injury and consequent risk of fatality. Failure to deploy properly and achieve this minimum required impact surface area was common with smoothbore barrels. However, the same square beanbags fired through a rifled barrel are spun open at the muzzle by the centrifugal forces acting upon the beanbag rotating on its axis, according to "12 Gauge Beanbag Fatality Risk Investigation" by D. MacPherson, D. Hudson and R. Maruoka in the Fall 2000 "Wound Ballistics Review," reducing penetration risk from unopened bags. Without penetration, the only potential for serious injury is that resulting from blunt trauma. Avoiding head and neck impacts, according to "Citizen Injuries from Law Enforcement Impact Munitions" by D. Klinger and K. Hubbs in the same issue of "Wound Ballistics Review" and "Modeling Blunt Trauma from Projectile Impact" by D. MacPherson in the Winter 2002 "AFTE Journal," can adequately manage this risk. For subjects likely to have brittle bones (the elderly and methamphetamine abusers), upper chest impacts should be avoided.
Responding to the new information, the LAPD changed the primary aimpoint from the sternum to the belly button and trained for point-of-aim at secondary targets such as hands and legs. In 2000, the LAPD retrofitted its arsenal of 300 beanbag shotguns with rifled barrels. At the same time, the LAPD made vivid green markings on the shotguns to distinguish them from regular duty shotguns, consistent with LAPD color-coded weapon systems, according to "Managing Your Training Risk" by R. Webb and L. Salseda in the August 2002 issue of "Law Enforcement Technology." The next step involved a closer study of the beanbag ammunition and its physical composition and performance.
Sock round issues
Although sock rounds have been touted as an answer to the injury problem, testing indicated that when fired through a smoothbore shotgun, these rounds penetrate gelatin, unless the velocity is below 250 feet per second. Most conventional sock rounds limit penetration potential by keeping the projectile velocity below the penetration threshold. These sock rounds rely on the velocity decay of the projectile (standoff distance of 30 feet) and the resilience of skin as a penetration barrier. The 30-foot standoff distance is very limiting, and relatively low-velocity projectiles are less effective (pain compliance) than those with a higher velocity.
The LAPD conducted beanbag performance studies that have a depth of analysis and testing that is unprecedented for a law enforcement agency. The collaboration of LAPD technical specialists involved several hundred hours of mathematical modeling, laboratory testing and practical experience.
The goal of these studies was the creation of a more effective beanbag that is deployable at shorter range without penetration risk. The concept was a higher velocity customized sock round without a tail fired through a rifled barrel. This would open up to form a disc and strike the target at the maximum expansion diameter to prevent penetration.
Developmental testing and adjustments resulted in a beanbag cartridge specification that had very strict requirements for accuracy, velocity variation, the diameter of the impacting beanbag and the integrity of the beanbag during impact. The LAPD offered no design assistance to manufacturers and treated its activities as proprietary. All beanbag cartridges submitted for consideration were subjected to the same battery of tests outlined in the specification to evaluate the required performance parameters. Three out of four manufacturers had significant non-compliances and were rated unsatisfactory.
The beanbag rounds submitted by Combined Tactical Systems were far superior to the other submissions and secured the LAPD contract. The final outcome is a highly effective, low-risk, three-part system that requires a proper aimpoint, specifically designed beanbag ammunition and rifled barrel shotguns.
LAPD scientists tried without initial success to influence department policy regarding the deployment range of this new beanbag system. In 2005, under the leadership of Chief William Bratton and his forward-thinking command staff, the LAPD revisited this issue and revised its minimum deployment distance to 5 feet. This minimum range is driven by tactical considerations when deploying shoulder weapons, not penetration risk. Both analysis and tests confirm that the beanbags are essentially fully deployed 2 feet from the muzzle of a rifled barrel and do not penetrate ballistic gelatin. The maximum range is 45 feet, and the primary aimpoint is the belly button with secondary targets of hands and legs.