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In principle, handgun recoil is predictable using conservation of momentum and known mechanical laws. In practice, recoil is often considered subjective. The current study employed high speed video recording at 10,000 frames per second to quantify recoil of 11 different pistol loads representing a range of bullet weights and velocities in three different cartridges (9mm NATO, .40 S&W, and .357 SIG) fired from the same Sig P229 auto-loading pistol with the appropriate caliber barrel. Kinematic variables quantified by analyzing the video included: slide velocity, frame velocity, frame angular velocity, slide acceleration, frame acceleration, and frame angular acceleration. The correlation of these quantities with bullet momentum estimates suggests that the video method is reliable for quantifying handgun recoil and shows promise for testing models purporting to predict handgun recoil from mechanical laws. Future work should be able to test effects of recoil reducing devices and determine which kinematic variables are the best predictors of ergonomic effects such as accuracy and shot-to-shot time intervals.

The subject of this research is multi-segmented, telescoping, beam-like structures, which represent an important class of engineering systems with, in general, nonuniform geometric and physical parameters. The distributed parameter Euler-Bernoulli sectioning methodology applied to such structures produces a transcendental eigenvalue equation that requires a numerical root-funding algorithm. This study provides evidence that for continuous system upper modes, root finding algorithm is subject to numerical instability due to the finite precision associated with software and hardware used for the computations. The results obtained after extensive numerical computation and analysis of three-segment cantilever telescoping beams with two lap joints, yield new insights into the prediction of the numerical instability and the role computational issues may play in the solution of distributed parameter eigenproblems.

This paper presents high speed video analysis of 11 service caliber lead-free pistol bullets impacting Clear Ballistics Gel® with the dual purpose of assessing the equivalence of Clear Ballistics Gel® and calibrated 10% ballistic gelatin as test media and providing an initial assessment of wounding and incapacitation potential of these 11 service caliber loads. The present study suggests that Clear Ballistics Gel® results in lower retarding forces, erratic expansion, greater variations in penetration depth, and larger average penetration depths than calibrated 10% gelatin. Taken together with other results, testing in Clear Ballistics Gel® should only be used to identify candidates for further testing in calibrated 10% ballistic gelatin; it should not be used for the selection of duty ammunition without further performance testing in calibrated 10% ballistic gelatin. Depending on the wound profile and penetration desired for a given application, several loads analyzed here may warrant additional study. The Liberty Civil Defense 60 grain lead-free hollow point had the largest peak retarding force, temporary cavity, and permanent cavity while meeting the oft-cited minimum penetration requirement of30 cm.

Due to concerns about environmental and industrial hazards of lead, a number of military, law enforcement, and wildlife management agencies are giving careful consideration to lead-free ammunition. The goal of lead-free bullets is to gain the advantages of reduced lead use in the environment while maintaining equal or better terminal performance. Accepting reduced terminal performance would foolishly risk the lives of military and law enforcement personnel. This paper uses the established technique of studying bullet impacts in ballistic gelatin to characterize the terminal performance of eight commercial off-the-shelf lead-free handgun bullets for comparison with earlier analysis of jacketed lead bullets. Peak retarding force and energy deposit in calibrated ballistic gelatin are quantified using high speed video. The temporary stretch cavities and permanent wound cavities are also characterized. Two factors tend to reduce the terminal performance of these lead-free projectiles compared to similar jacketed lead designs. First, solid copper construction increase barrel friction, which reduces muzzle velocity and energy, and thus reduces the ability of the bullet to exert damaging forces in tissue simulant. Second, the lower density of copper requires a longer bullet for a given mass and caliber, which reduces remaining powdervolume in the brass cartridge case, which also tends to reduce muzzle velocity and energy. The resultsof the present study are consistent with earlier analysis showing that expansion is necessary to maximize the potential for rapid incapacitation of enemy combatants. In spite of some new non-expanding nose designs that moderately increase forces between bullet and tissue, the largest retarding forces and highest incapacitation potential requires expanding bullets which maximize frontal area.

This paper describes the development and characterization of modular, oxy-acetylene driven laboratory scale shock tubes. Such tools are needed to produce realistic blast waves in a laboratory setting. The pressure-time profiles measured at 1 MHz using high speed piezoelectric pressure sensors have relevant durations and show a true shock front and exponential decay characteristic of free-field blast waves. Descriptions are included for shock tube diameters of 27 - 79 mm. A range of peak pressures from 204 kPa to 1187 kPa (with 0.5 - 5.6% standard error of the mean) were produced by selection of the driver section diameter and distance from the shock tube opening. The peak pressures varied predictably with distance from the shock tube opening while maintaining both a true blast wave profile and relevant pulse duration for distances up to about one diameter from the shock tube opening. This shock tube design provides a more realistic blast profile than current compression-driven shock tubes, and it does not have a large jet effect. In addition, operation does not require specialized personnel or facilities like most blast-driven shock tubes, which reduces operating costs and effort and permits greater throughput and accessibility. It is expected to be useful in assessing the response of various sensors to shock wave loading; assessing the reflection, transmission, and absorption properties of candidate armor materials; assessing material properties at high rates of loading; assessing the response of biological materials to shock wave exposure; and providing a means to validate numerical models of the interaction of shock waves with structures. All of these activities have been difficult to pursue in a laboratory setting due in part to lack of appropriate means to produce a realistic blast loading profile.