Projectile with amorphous polymer tip

Abstract

Projectiles with amorphous polymer tips have an elongated body, the body having a forward end, the body having a rear end opposite the forward end, the body having an intermediate cylindrical portion between the rear and forward ends, the front end of the body defining a cavity, a nose element, at least a portion of which is received in the cavity, wherein the nose element is an elongated body having opposed ends, and wherein the nose element is polymer resin having a glass transition point temperature greater than or equal to 185° C. The nose element may be a polymer resin that does not have a discrete melting point. The nose element may be a polymer resin having a glass transition point temperature less than or equal to 225° C. The nose element may be a polymer resin having a molding temperature melt point greater than or equal to 330° C.

Description

FIELD OF THE INVENTION[0001]This invention relates to firearms ammunition, and more particularly to projectiles with expanding characteristics.BACKGROUND OF THE INVENTION[0002]For long-distance shooting, there is a trade-off between designing for aerodynamic performance, accuracy and terminal ballistics. Projectiles that are the most aerodynamic and accurate tend to be poor terminal performers when hunting game, and projectiles that expand effectively (especially at slower speeds after having traveled a great distance) typically lack the aerodynamic performance desired for hunting game at long ranges.[0003]Good aerodynamics, and accuracy are provided by boat-tail hollow point (BTHP) projectiles that are popular among match competitors. However, these do not humanely dispatch game animals in long-range hunting situations. Many hunting projectiles employ hollow points filled with pointed plastic tips that help to facilitate expansion and purportedly improve aerodynamics.[0004]Other ty...

AI Technical Summary

Benefits of technology

The present invention is an improved cartridge and bullet with a tip made of amorphous polymer. This new design solves the problems of previous designs and provides better long-range ballistics with reduced aerodynamic drag. Overall, this new design improves the performance of projectiles.

Problems solved by technology

Projectiles that are the most aerodynamic and accurate tend to be poor terminal performers when hunting game, and projectiles that expand effectively (especially at slower speeds after having traveled a great distance) typically lack the aerodynamic performance desired for hunting game at long ranges.

However, these do not humanely dispatch game animals in long-range hunting situations.

Other types of projectile tips have been employed, such as inserts formed of metals like aluminum or bronze (as contrasted with tips formed of the projectile's copper jacket or lead core), which either fail to effectively expand or not provide adequate aerodynamics as needed for long range hunting or target shooting.

Furthermore, metal tips suffer substantial economic disadvantages compared to injection molded polymer tips.

Metal tips also require machining to form a suitable shape to achieve acceptable aerodynamics, and thus add unacceptably to the cost of a tipped projectile.

Other materials serving as alternatives to polymers are also prohibitively expensive.

Because of the very low glass transition point of the crystalline polymers, coupled with their low melt points, they are unable to withstand high temperatures and anything but modest velocities in ballistic applications without losing their shape.

It has been unexpectedly discovered that these conventional crystalline polymers are impairing long-range effectiveness of polymer tipped projectiles because they are melting and deforming because of heating associated with the supersonic airflow around the projectile.

Because of the very low glass transition point of the currently used Delrin® and nylon polymers, and their corresponding low melting points, these plastics can only be used at low velocities without deforming and losing their shape.

Instead of a pointed tip, the tip is melting and ablating in the high temperature supersonic airflow and flattening, thereby increasing its frontal area as it travels downrange and causing increased drag.

Current designs of crystalline polymer tips suffer from the tips melting and flattening above velocities of 2,400 fps because of aerodynamic heating.

The melting of the tips causes the tip diameter, or meplat diameter, to become larger, which increases the aerodynamic drag on the projectile.

This limited data at short ranges has masked the issue of melting crystalline polymer tipped projectiles because it is within the window of time / distance for the effect to begin to become significant and suffer from the limitations of only two data points versus hundreds obtained via Doppler radar.

The use of only three chronograph screens does not provide the resolution necessary to see the problem, and uses a very large average, which further masks the problem.

This phenomenon has been hypothesized, but no definitive work has ever been done previously to establish the heat transfer rate / times that occur in order to establish that crystalline polymer tip melting and deformation has a significant effect on long range projectile performance.

Images