The Frangible
Advantage Mic McPherson
Cross-sections of selected 22-caliber varminting bullets. Left to right: Berger 30 VHP, 40 VHP, and 50 VHP; Nosler 40 BT; Sierra 40 BlitzKing; Hornady 40 V-Max and 60 V-Max; Barnes 36 Varmint Grenade (VG); Hornady 35 NTX; Nosler 35 BTLF. I discussed basic characteristics of most of these in the text. Worth noting is that core of the VG is a solid copper-based composite; core of the NTX seems to be a very similar material; main core of BTLF is compressed copper shot, which has essentially zero airspace, with a plastic cap interposing ballistic tip and main core (many core particles have fallen out, which is useful to demonstrate core design, where these have not fallen out it is easy to see how little core-void exists). Notice significant solid base on BT. This is why these bullets tend to be more effective against larger species of vermin. This also is why it is so easy to develop accuracy loads with these bullets (solid base is significantly less apt to asymmetrically deform as bullet transitions from case to rifling. Relatively hard and resilient cores of frangible bullets should offer the same advantage). (Epoxy used to fix bullets infiltrated tips of hollow-point bullets to varying degrees – visible as darkened area inside mouth of these bullets.)
SYNOPSIS:
Frangible varminting bullets have the obvious advantage of limiting rico- chet hazard. But, for varmint hunters, these bullets have other significant ad- vantages. Among those are increased ef- fective range, reduced recoil, and, often, a usefully flatter trajectory. Here I will address these in some detail. A DISCLAIMER
The more sophisticated the de- sign, the more opportunity for unan- ticipated variations to negatively affect performance. A plastic-tipped bullet is more sophisticated than a conventional hollow-point bullet is and a frangible core bullet is far more sophisticated yet. Rather than discussing all the variables that might possibly defeat the function of a frangible bullet, I will offer an ex- ample from a different era. Many decades ago, Speer invented primer-powered ammunition intended for safe indoor target practice with a rudimentary bullet trap. This product worked very well. About the same time, Speer intro-
Page 40 Winter 2013
duced shot cups for use in pistol and revolver cartridges. During in-house design evaluation, these worked won- derfully in everything they tested. Wide velocity variations in the load and wide burn rate variations in the propellant used and wide shot size variations did not seem to matter. The things just worked as intended – excellent snake and small pest killers out to about 15 feet, at least. So, for marketing, Speer came up with a color scheme to designate shot- cup caliber and to make the product a bit sexier – it is well proven that we all respond to colors better than we do to plain transparency. Speer produced millions of the
things in various calibers and filled the product pipeline so retailers across the country could stock this useful new item. A minor disaster ensued. When handloaders tried these in-
teresting new devices, the cups for some calibers would not disintegrate at all. Other sizes were problematic – worked sometimes with some loads.
The problem was that addition of
parts-per-million of the dyes added to the plastic changed the characteristics of the plastic so radically that many colors were so tough that those acted as a bul- let, rather than as a frangible jacket that shattered in the barrel and disintegrated upon barrel exit.
Nobody in the plastics industry
predicted this. Speer had to find it out the expensive way. Frangible bullets suffer the same
potential sensitivity to material qual- ity and composition. The following discussion ignores this aspect and in it I assume that the related manufactur- ers have the quality-control issues well in hand and that their quality-control personnel continue to do so. Keeping in mind that any manufacturer can have quality-control problems and that at least one of the majors has developed something of a reputation for releasing products that do not work (at least not in the initial incarnation), the following discussion assumes best feasible design and quality for desired performance.
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