Shot Cup Wad with Deployed Petals for Pellet Pattern Control

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Solution Overview

Problem

Conventional shotshell wads experience radial spreading and inconsistent pellet patterns due to uneven air pressure, leading to unpredictable shot placement and trajectory issues.

Innovation Solution

A shot cup design with a rear cylinder that forms petals upon firing, using impressions or weakened areas to deploy radially and decelerate the wad, maintaining a cylindrical shape and facilitating a tighter pellet pattern by separating the wad from the shot pellets quickly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If air pressure is used to deploy petals in conventional shotshell wads, then the wad can separate from the payload, but the air pressure causes radial spreading of petals and disperses shot pellets in a wider pattern

Engineering Contradiction:
Improvewad separation from payloadVSAvoidshot pattern consistency
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The wad is divided into multiple petal sections that can deploy independently. Each petal is separated by score lines or thin webs that allow controlled deployment, preventing radial spreading while maintaining reliable separation from the payload.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the wad have different properties - the petal regions are designed to be flexible and deployable, while the central body remains rigid to maintain alignment. The score lines create localized weak points that control where deformation occurs, preventing unwanted radial spreading.

Inventive Principle:
Principle #3Local quality

2Speed

If petals are deployed using air pressure, then the wad can slow down, but uneven air pressure causes uneven deployment and veering of the shotshell wad

Engineering Contradiction:
Improvewad decelerationVSAvoidwad trajectory stability
Core Design Contradiction:
SpeedVSStability of the object's composition

Solution Approach 1:

Score lines or pre-formed seams are created in the petal regions before firing. These pre-defined deformation paths ensure that petals deploy in a controlled, symmetric manner, preventing uneven deployment and trajectory veering while still achieving rapid deceleration.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The petal design creates equal deployment conditions across all petal sections through symmetric scoring and uniform material thickness. This ensures that air pressure acts equally on all petals, resulting in simultaneous and uniform deployment that maintains wad stability and prevents veering.

Inventive Principle:
Principle #12Equipotentiality

3Strength

If the wad remains in contact with shot pellets for extended time, then the wad can support the payload, but the shot pattern becomes inconsistent and unpredictable

Engineering Contradiction:
Improvepayload supportVSAvoidshot pattern placement
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The wad transitions from a static, rigid structure to a dynamic, deployable structure. Upon firing, the petals rapidly deploy and the wad separates from the payload, minimizing contact time. This dynamic separation ensures consistent shot pattern placement while maintaining payload support during the critical initial phase.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The wad quickly performs its support function and then rapidly separates from the payload through petal deployment. This brief, intense support phase followed by rapid separation ensures that the payload receives adequate support without prolonged contact that would cause pattern inconsistency.

Inventive Principle:
Principle #21Skipping (Rushing through)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution ensures a more consistent and centered downrange pellet pattern by rapidly separating the wad from the shot pellets, maintaining alignment and reducing pellet dispersion, resulting in a denser and more accurate shot spread.

Implementation Method 1

a propellant powder to be ignited by the primer. The propellant powder can produce high pressure gas that can propel the payload from the chamber

Methodology Applied
Scientific EffectCombustion: Combustion

Implementation Method 2

The pressurized gas will expand within the rear cylinder so as to propel the wad and the payload received in the forward cylinder down a firearm barrel

Methodology Applied
Scientific EffectGas expansion: Pressure Increase

Implementation Method 3

heat from combustion of the propellant can aid in the rupture of the rear cylinder along the impressions for formation of the petals

Methodology Applied
Scientific EffectThermal heating: Heating

Implementation Method 4

The deployed petals can rapidly slow the wad to provide and/or facilitate a substantially rapid separation between the wad and the shot pellets

Methodology Applied
Scientific EffectAir resistance: Drag

Data Source

PatentUS9778002B2Shot cup wad
Publication Date: 2017.10.03 AMMUNITION OPERATIONS LLC
  • US9778002B2 patent drawing
  • US9778002B2 patent drawing
  • US9778002B2 patent drawing

AI summary

A wad or shot cup having a forward cylinder portion receiving a payload and a rear cylinder portion receiving a charge of propellant. One or more latent deceleration features can be formed in a surface of the sidewall extending along the rear cylinder portion. The latent deceleration features can be spaced apart from a rearward end of the shot cup and can be deployed to form deceleration petals after the shot cup is fired from a firearm. A series of longitudinal slits can be formed in the forward cylinder portion so that a portion of the sidewall expands radially adjacent the longitudinal slits after the shot cup is fired from a firearm for urging at least a portion of the payload to exit the forward cylinder portion.