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THE IWBA HANDGUN AMMUNITION SPECIFICATION PACKAGE
This IWBA Handgun Specification Package contains this cover page, a specimen handgun ammunition specification (the IWBA Handgun Ammunition Specification), and a supplement that explains various details and decisions that are related to the IWBA Handgun Ammunition Specification. The IWBA Handgun Ammunition Specification contains blanks for important parameters that must be supplied by the purchaser; the supplement provides recommendations for these values that are appropriate for typical purchasers. The recommendations are a useful guide and can be selected, but the purchaser has the responsibility for selecting parameter values that best satisfy his particular needs. The IWBA Handgun Ammunition Specification will satisfy the needs of most users when used verbatim, but users with special needs can modify it and/or add to it. This IWBA Handgun Ammunition Specification package was developed by the IWBA with the assistance of participating handgun ammunition manufacturers.
The IWBA Handgun Ammunition Specification has been designed to be an example of a specification that is precise and realistic in format, with identified parameters that can be specified by the user to satisfy his requirements and desires. The requirements have been selected to identify the parameters that require definition by the purchaser and to eliminate requirements that are ambiguous, technically unachievable, irrelevant, impractical to verify, or otherwise unsound. Use of this IWBA Handgun Ammunition Specification as a guide should make communication between manufacturer and purchaser much more satisfying and advantageous to both parties.
Writing a good specification requires detailed knowledge in various technical disciplines that is not available in most organizations. In particular, it is not always obvious why various requirements common in handgun ammunition specifications are unsound. The supplement that follows explains reasons for presence or absence of requirements in the IWBA Handgun Ammunition Specification, and in some cases provides other related information. This supplement is not part of the IWBA Handgun Ammunition Specification, its function is to provide additional information for purchasers. The section numbering of the supplement and specification are identical for purchaser convenience in cross referencing. Some sections of the specification are completely self explanatory and have no corresponding section in the supplement.
This specification focuses on terminal ballistic performance, and does not place separate detailed requirements on parameters that the manufacturer must control during the production process in order to produce reliable terminal ballistic performance. This specification is directed at requiring ammunition with the most reliable expansion in the shooting scenarios most common and important to the majority of law enforcement officers clothed humans not protected by hard barriers. Barrier performance issues are discussed in the supplement.
The wording of the IWBA Handgun Ammunition Specification assumes that the purchaser will do acceptance testing of the purchased ammunition. This acceptance testing is strongly recommended, but can be eliminated if desired by appropriate wording changes. Law enforcement agencies that want information on acceptance or other ammunition testing should contact the IWBA office (PO Box 701, El Segundo, CA 90245) with their requests.
All material in the Wound Ballistics Review is copyrighted and cannot be photocopied without permission. Permission is hereby given to all IWBA members and all law enforcement agencies to photocopy or otherwise reproduce this IWBA Handgun Ammunition Specification Package for any use associated with ammunition procurement.
"The IWBA Handgun Ammunition Specification Package." Wound Ballistics Review, 3(3): 22-27; 1998.
IWBA Handgun Ammunition Specification
|The following definitions apply to these terms used in this specification.|
|1.1||"mean" is the arithmetic average value of a sample of parameter measurements.|
|1.2||"standard deviation" is the Root Mean Square dispersion from the mean in a sample of parameter measurements (i.e., the square root of the sample estimate of variance).|
|1.3||"standard gelatin" is gelatin that gives 8.5 cm of penetration by a standard steel BB with an entry velocity of 590 ft/sec.|
|1.4||"penetration depth" is the depth of penetration in standard gelatin from the entry point to the most forward point on the projectile in its final resting position.|
|2.1||All ammunition shall conform to standards set by the Sporting Arms and Ammunition Manufacturers Institute (SAAMI) unless otherwise specified in the description of the round.|
|2.2||Bullet design shall be jacketed with controlled expansion to meet the requirements of Section 6.0.|
|2.3||Powder shall be smokeless, clean burning, and treated to reduce muzzle flash.|
|2.4||Case shall be metallic boxer primed.|
|2.5||Primer shall be non corrosive, sealed to be water resistant.|
|2.6||Each cartridge headstamp shall show manufacturers symbol and appropriate designation.|
|2.7||Packaging shall be 50 cartridges per box, not more than 20 boxes per case. Lot number shall be printed clearly on each box.|
|3.0||Physical Parameter Specifications|
|3.1||Caliber shall be __________.|
|3.2||Mean bullet weight shall be at least __________ grains but not more than __________ grains.|
|3.3||Mean bullet velocity shall be near but not greater than the maximum velocity compatible with SAAMI maximum pressure standards.|
|The purchaser reserves the right to reject ammunition that does not demonstrate acceptable accuracy in his issue handguns.|
|The purchaser reserves the right to reject ammunition that does not demonstrate acceptable functional reliability in his issue handguns.|
|The penetration depth specifications in this section are stated as hard requirements, but it is recognized that these requirements are stressing and that requirement violation by a fraction of an inch is of minor consequence. Accordingly, the purchaser reserves the right to accept ammunition having minor violations in these penetration requirements. Penetration performance statistics will be nominally conducted with a sample size of 10 test shots, but the purchaser reserves the right to test a larger sample if this seems desirable to him.|
|6.1||Penetration requirements in standard gelatin|
|6.1.1||The standard deviation of the penetration depth shall be less than __________ inches.|
|6.1.2||The mean penetration depth shall be greater than __________ inches and less than __________ inches.|
|6.1.3||The goal is to avoid all bullet fragmentation and/or jacket separation. The requirement is that the largest bullet segment weight shall be at least 90% of the mean unfired bullet weight in at least 90% of penetrations.|
|6.2||Penetration requirements in standard gelatin after penetrating 4 layers of heavy denim (weight 16 ounces per square yard). The 4 layers of denim are placed against the gelatin without deliberate spacing between layers, but are not compressed in place by any kind of fixture.|
|6.2.1||The standard deviation of the penetration depth shall be less than __________ inches.|
|6.2.2||The mean penetration depth shall be greater than __________ inches and less than __________ inches.|
IWBA Handgun Ammunition Specification Supplement
|1.1,1.2||The parameters "mean" and "standard deviation" are used in statistical sampling problems of all kinds. While it might seem that specification of maximum or minimum values would better satisfy user requirements, this kind of specification is technically unsound unless an adequate number of tests is provided to deal with stochastic sampling issues. Satisfactory approximations to the mean and standard deviation can be obtained with a relatively modest number of samples for the important parameters in the ammunition specification; obtaining sufficient samples to reasonably validate a maximum or minimum requirement usually requires impractical costs.|
|1.3||This definition of "standard gelatin" is selected because various studies have shown that this standard provides a good correlation with penetration in typical soft tissue.1 No similar studies drawing different conclusion are known. Some organizations are using different standards, but the source of, and justification for, these alternative standards is uncertain. It is possible that these different standards have been chosen simply because the users have found that calibration penetrations in their 10% gelatin mixtures do not average the 8.5 cm (about 3.35 or 3 11/32 inches) penetration depth at 590 ft/sec of standard gelatin. Such a standard change represents a complete lack of understanding of the purpose of and the need for calibration. All experienced users are aware of the significant lot to lot variation in the gelatin delivered by Kind & Knox. There is also reason to believe that the typical gelatin delivered today is not identical to the typical gelatin delivered 10 years ago, and no assurance that gelatin in the future will have exactly the same typical properties as gelatin delivered today. Under these circumstances, there is simply no credible justification for not maintaining a fixed standard unrelated to the properties of the specific gelatin being used. Calibration of gelatin used in penetration testing is mandatory, and this calibration data can be used to reliably correct penetration depths measured in non-standard gelatin to the depth that would have been obtained in standard gelatin.1,2 The specification requirements assume that this process will be implemented with all test data. The existence of this capability to reliably correct data to standard gelatin conditions makes the early approach of defining an "acceptable range" of gelatin calibration depth technologically obsolete.|
|Added Definition for this Supplement: "barrier" is any material impacted by the bullet prior to its entry into gelatin.|
|2.3||There is a tradeoff between flash suppression and clean burning (cleaner burning powder has increased flash and vice versa). This tradeoff is a detailed technical problem that is difficult to quantify simply, but it has been worked by many of the manufacturers for their law enforcement ammunition lines. The purchaser should state his objectives to the manufacturer, who can then select a powder that best meets this objective. Since all manufacturers usually have access to the same powders, this powder choice will not usually be a discriminator in ammunition selection. The purchaser can fire the final product in low light conditions to show that his objectives have been met.|
|3.0||Physical Parameter Specifications|
|3.1||The purchaser must define the caliber of ammunition desired.|
|3.2 a)||The purchaser must define the mean bullet weight range desired. Suggested maximum and minimum values are 145 and 150 for 9mm, 177 and 182 for .40 S&W or 10mm, 227 and 232 grains for .45ACP. These recommended ranges of permissible mean bullet weights correspond to the conventional maximum bullet weights in the calibers. The performance loss with slightly lighter bullets is not significant and might allow some manufacturers to reduce some costs; if desired, this can easily be implemented by slightly lowering specified minimum for the weight range. These suggested values are compatible with the belief (based on knowledge of the dynamics of bullet penetration1) that handgun bullets should be near the conventional maximum value for the caliber in standard pistol barrel lengths for best wounding efficiency. Purchasers who disagree with this belief can obviously specify whatever bullet weight they desire in this section. See Section 3.3 for comments on compact pistol ammunition.|
|3.2 b)||Note that the variation of bullet weight from this mean does not have to be specified because compliance with specifications in Section 6.0 requires the manufacturers to maintain tight control on bullet weight and other parameters related to bullet manufacturing tolerances.|
|3.3 a)||The purchaser can specify a mean bullet velocity, but this is not wise. The user can specify a lower value than the maximum velocity compatible with SAAMI maximum pressure standards, but this is not advisable because the bullet expansion may be less reliable at lower velocities. The bullet design is intimately connected with the bullet velocity, use of JHP handgun bullets at velocities significantly different (lower or higher) from the design velocity is very ill advised. The purchaser usually does not have enough information to make a realistic specification velocity, and this is best left to the manufacturer. The actual velocity achieved will depend somewhat on the pistol used, but the purchaser is fully protected because the Section 6 performance requirements must be satisfied with the offered ammunition.|
|3.3 b)||Note that the velocity achieved may be reduced significantly in the shorter barrels of some "compact" pistols (with a probability of at least some loss in expansion). Ammunition designed for both standard and compact pistol barrel lengths may not achieve optimum performance in both pistol types. If ammunition for compact pistols is desired, it can be specified separately. In any case, the purchaser should acceptance test the ammunition in the pistols to be used.|
|The accuracy of ammunition from major manufacturers in SAAMI test barrels easily exceeds any reasonable practical accuracy requirements. The purchaser should test ammunition accuracy in his issue handguns, but should also recognize that any accuracy problems are most likely a result of either the handguns used or the rest setup used in the testing. Occasionally, some ammunition may not shoot well in some guns for reasons that are neither well understood or easily resolved. It is better for the purchaser to decide if he has this problem as a result of appropriate testing than it is to set an arbitrary standard a priori.|
|Occasionally, some ammunition may not function in some guns for reasons that may or may not be well understood or easily resolved. The obvious goal is no function failures, but each purchaser must decide what functional failure rate he can tolerate. Any functional failure problems should be worked cooperatively with the ammunition manufacturer. The purchaser can place a specific functional failure rate requirement in this section if he desires, but any specification requirement should include a complete description of the test protocol that will be used in the evaluation.|
|6.0 a)||Both understanding of terminal ballistics and improvements in handgun ammunition have been impeded by formulating performance in terms of hard limits (e.g., 12.1 inches of penetration is very good, but 11.9 inches is totally unacceptable). On the other hand, performance specification compliance evaluation is greatly simplified by considering all requirements as hard limits. The statement given recognizes this problem and avoids forcing the purchaser into actions not in his best interest while still specifying a reasonable standard.|
|6.0 b)||A sample size of 10 normally provides a satisfactory indication of performance, but the specification allows more testing to investigate any anomalous results at the discretion of the purchaser. In addition, purchasers who take delivery of large orders that have ammunition from more than one manufacturers lot may elect to do a combined lot acceptance testing that has less than 10 samples per lot, but more than 10 samples overall.|
|6.0 c)||It is absolutely mandatory that the test data correction procedure discussed in Section 1.3 discussion above be followed in processing the test results of this section in order to insure a valid interpretation of test results.|
|6.1||Penetration testing in standard gelatin is conventional, and provides the most common (but not the most important) performance measurement.|
|6.1.1||The standard deviation of the penetration depth is the best measure of consistency of bullet expansion, and is small in bare gelatin for well designed bullets. The recommended value of this parameter is 0.6 inch, which most well designed JHP bullets will easily meet. Specification of (or acceptance of) a slightly larger value (e.g., 0.8 inch) does not have serious performance consequences (see discussion under Section 6.0).|
|6.1.2||Most physicians knowledgeable in wound trauma believe that adequate penetration depth is the most important single property in handgun ammunition. The appropriate value for minimum penetration depth has generally been assumed to be 12 inches ever since the first FBI wound ballistics meeting in 1987. Unfortunately, this assumption has often been interpreted very simplistically (i.e., 12.1 Inches of penetration is good, but 11.9 inches of penetration is no good), but the real situation is more complicated. The problem is the possibility that the bullet will require an unusually large penetration to reach vital structures well inside the body. This can occur when the bullet must traverse non-critical tissue; e.g., the extended arm of an assailant aiming his handgun, and/or an unusual bullet path angle in the torso, and/or an unusually fat or beefy individual. The probability of needing this extra penetration is a judgment call, but most people believe it is a significant factor and much more important than the relatively modest increase in expanded diameter achieved by reducing penetration depth (e.g., approximately 30% increase in expanded bullet diameter is achieved by designing to an 8 inch penetration depth rather than 12 inches). This is the reason the professional wound ballistics community specified the 12 inch minimum penetration even though they are well aware that an 8 inch penetration is usually adequate. The suggested specification values for mean penetration depth are greater than 12.5 inches and less than 14.0 inches. Even at the limit of minimum value of this range (12.5 inches) and the limiting value of standard deviation (0.6) in Section 6.1.1, about 80% of the penetration will be greater than 12 inches and essentially all will be greater than 11 inches. This bare gelatin test provides a lower limit on penetration because most shootings will involve at least some clothing; slightly less expansion and slightly deeper penetration can be expected in typical service use.|
|6.1.3||This specification is included to prevent unsound bullet designs that over expand and break up (which reduces effectiveness in handgun bullets) or bullet designs that tend to separate the jacket early in the penetration. Some bullet designs occasionally shed their jackets near the end of the penetration; this is not desirable, but shedding the jacket after about 12 inches of penetration is not a serious flaw. Note that tests have shown that bullet expansion in bare gelatin will usually be slightly greater than expansion in tissue; the theoretical basis for this slight difference is understood.1 As a result, bullet designs that do not break up in bare gelatin are unlikely to break up in soft tissue.|
|6.2||Most expansion failures of JHP handgun bullets reported in actual shootings where hard barriers are not involved are probably due to factors that effectively plug up the hollow point cavity and reduce pressure in this area, although the dynamics model that occasionally leads to this result is not completely known in detail. This requirement in the IWBA Handgun Ammunition Specification is designed to force JHP bullet designs that expand much more reliably against soft barriers (hard barriers are discussed in more detail below). This requirement was selected after experimentation to provide a standardized, inexpensive, and precisely defined soft barrier that was a stressing but reasonable protocol for ammunition evaluation; it does not represent a simulation of specific clothing. The JHP bullet design features required to satisfy this requirement are well understood, and ammunition having these design features expands much more consistently and reliably against soft barriers than ammunition without these design features. The heavy denim specified has a nominal weight of 16 ounces per square yard, and the actual weight seems to be held within 2% of this nominal in different lots (this variation is too small to be significant). This denim is soft to the touch and does not have starch, sizing or other stiffeners. Unfortunately, cloth does not seem to have the kind of specifications that make it easy to define for the retail purchaser; apart from weight, the selection is by feel and appearance (most seamstresses seem to find this very satisfactory). As a (non-profit) service to users, the IWBA office (PO Box 701, El Segundo, CA 90245) will ship a 36 inch by 60 inch sample of this denim by priority mail to addresses within the USA for $20 ($30 for foreign addresses).|
|6.2.1||The standard deviation of the penetration depth is the best measure of consistency of bullet expansion, and is an important indication of the quality of bullet design. The standard deviation in this section can be expected to be somewhat larger than in Section 6.1.1 (bare gelatin), but should still be reasonably small with well designed bullets. The recommended value of this parameter is 0.8 inch. Specification of (or acceptance of) a slightly larger value (e.g., 1.0 inch) does not have serious performance consequences (see discussion under Section 6.0).|
|6.2.2||The mean penetration depth in this section can be expected to be somewhat larger than in Section 6.1.2 (bare gelatin), and represents a reasonable upper bound on the mean penetration depth in service. The suggested specification values for mean penetration depth are greater than 13.0 inches and less than 16.0 inches. The realities of JHP bullet performance eliminate any practical concern that penetration depth will be inadequate in this test for any ammunition with adequate penetration in the Section 6.1 test. A one inch increase in maximum penetration depth corresponds to approximately a 0.02 inch reduction in expanded diameter, which is not a significant concern as long as the requirement of Section 6.2.1 is met. The general discussion of penetration depth in Section 6.1.2 also applies here.|
Comments on Hard Barriers
Penetration in standard gelatin after penetrating various hard barriers has been a factor in handgun ammunition design since these were made factors in the FBI handgun ammunition test protocol in 1989. This consideration was initially useful because bullet designs at the time were very unsophisticated by current standards, but hard barrier requirements are now forcing bullet designs that are less effective in shooting scenarios without these barriers. In effect, optimizing JHP performance in the presence of soft barriers and accepting the performance of the resulting bullet design through hard barriers is the best approach for almost (if not all) law enforcement agencies; this approach is implemented by this specification. More detailed discussion of the various hard barrier types follows.
Automobile windshield glass:
Automobile windshield glass is an important barrier for some (but not all) law enforcement agencies, so it might seem that some requirement associated with this barrier would be appropriate in an ammunition specification. The problem with such a requirement is associated with the dynamic forces on the bullet as it penetrates the glass. Careful testing has shown that the forces on the bullet are so large during penetration that any bullet that expands in soft tissue has no effective resistance to deformation from glass contact.3 As a result, attempting to improve JHP bullet performance through automobile windshield glass can significantly compromise performance through soft barriers without making any useful improvement in performance through the glass. A specification for performance through automobile windshield glass can be included, but this is not recommended because the probable result is more likely to be unintended negative consequences than ammunition improvement. Performance of well designed JHP bullet designs through automobile windshield glass is usually acceptable.
It is possible to define scenarios where penetration through walls or doors is desired to incapacitate an assailant, but these scenarios are an extremely small percentage of all shootings for most law enforcement departments. In fact, bullets contacting building materials are far more likely to represent misses where effective bullet penetration is not wanted because it represents a threat to non-combatants. It is possible to make JHP handgun bullets more effective in scenarios requiring penetration of building materials, but usually only by making expansion less reliable in scenarios requiring penetration of soft barriers. Designing JHP handgun ammunition to perform well in the building material stages of the FBI handgun ammunition test protocol requires this compromise. Law enforcement departments who do not have a significant fraction of shootings through building materials should use ammunition designed to this IWBA Handgun Ammunition Specification rather than ammunition designed for performance in hard barrier scenarios in order to obtain better expansion reliability.
Comments on Expanded JHP Bullet Diameter
The absence of any mention of expanded JHP diameter in the IWBA specification is not an oversight, expanded JHP bullet diameter is omitted because it is not independent of penetration depth. A JHP bullet of any weight, velocity, and penetration depth has an effective expanded diameter that produces the forces on the tissue during bullet penetration, and this effective diameter cannot be changed without changing at least one of the other parameters. In effect, bullet weight, velocity and penetration depth define the effective expanded bullet diameter. Penetration depth is easy and unambiguous to measure, but effective expanded bullet diameter is difficult to estimate with useful accuracy because the expanded periphery is inevitably irregular and not easily related to the effective expanded diameter. As a result, measured expanded bullet diameter is much less useful than penetration depth as a performance parameter in an ammunition specification. As a rule of thumb, effective expanded diameter is about 50% to 60% larger than original JHP bullet diameter when penetration is adequate. If bullet weight, velocity and penetration depth are specified, effective bullet diameter can be "required" to be any value not greater than it actually is, but this is pointless. There is no point in "requiring" effective expanded bullet diameter to be larger than allowed by the dynamics of penetration.
1) MacPherson, Duncan, "Bullet Penetration Modeling the Dynamics and the Incapacitation Resulting from Wound Trauma." Ballistic Publications, El Segundo, California. 1994
2) MacPherson, Duncan: "A Simplified Penetration Depth Correction for Data Taken in Non-Standard Gelatin." Wound Ballistics Review, 2(1): 41-45; 1995.
3) MacPherson, Duncan and Fincel, Ed, Lt., California Highway Patrol, "Windshield Glass Penetration". Wound Ballistics Review, 2(4): 35-39; 1996.
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