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Originally Posted by
Schmetallurgy
I'm saying that state of the art JHPs recovered from humans typically have expanded profiles more like 4LD test bullets than bare gel test bullets, i.e., with less expansion, which I suspect is due to human bodies rarely presenting a sufficiently homogeneous and gel-equivalent soft tissue wound path during the expansion phase, combined with instances of there being sufficient clothing to play a role in limiting expansion. There has to be some mechanical explanation for this tendency in recovered bullet profiles observed by Doc and others, and I suspect that is it.
There certainly is; impacting bone or other "hard" solid that partially plugs the cavity and thus reduces stagnation pressure and expansion; also impacting fat, not muscle. However, impact with muscle is most likely NOT going to result in smaller average diameter than impacting bare gel. Anyway, more modern JHPs are less and less sensitive to the cavities being plugged and thus experiencing expansion reduction -- unlike the days when Wolberg published his findings where expansion in soft tissue was all over the place -- including a finding that there can be more penetration in soft tissue, but as a result of much less expansion than in bare gel (especially if lung tissue and fat are substantial part of the wound track). There are very good mechanical reasons why, short of substantial wound track in the lungs, penetration in the body soft tissues (same frontal area and velocity) is typically a few inches LESS than in SOG (even without any bones).
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There are earlier comments in this thread referencing some rare instances of jacket separation by HSTs in auto-glass tests. I suspect that is as much to blame for the change as anything, because Federal's gel numbers haven't seemed to be a topic of concern here, and thus I suspect more broadly, until now-- something I attribute to high quality independent test data and street results supporting the old design.
There's better for windshields than HST, but that's another issue.
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As for such jacket separations, I suspect they're rare enough, and of limited enough functional significance with 147gr, especially when part of a volley of non-shedding bullets, so as to be outweighed by the benefits of greater max expansion increasing the likelihood of a critical vascular or nerve structure being damaged by a passing bullet. To me it's not just a question of total surface area, thus "volume of meat crushed," but odds of severing or crushing something especially efficient at causing rapid incapacitation. You don't have to take a chunk out of a large vessel to rapidly dump blood pressure, you just have to reach it and cut for a reasonable distance of contact; the blood pressure will ensure rapid outflow.
More tissue disruption is fine -- but not at expense of penetration so that vital tissue is reached AND disrupted.
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Therefore, I place more value on the area of the polygon produced by connecting the extreme edges of the petals (the area inside which contact will be nearly guaranteed) than I place on actual frontal area of the petal and core material (the area of direct displacement). I'm just trying to clearly illustrate my general preference, not to say I'm sitting here with calipers sketching out polygons from test bullets. However, this conceptual difference is also relevant because the gaps between the petals lower the resistance to penetration while, in my opinion, only minimally reducing critical wounding capacity-- within reason of course. HST has always appeared to exemplify this concept very well until now. HST likely also was able to penetrate sufficiently while expanding unusually large due to the prevalence of sharp frontal surfaces, when well expanded, which more efficiently cut through tissue thus retaining more energy for penetration.
Yes, HST bullet design is fine -- as long as it doesn't overexpand and thus underpenetrate.
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Of course there are other ways to prevent jacket separation. Locking bands and bonding come to mind. I've always thought the ideal bullet would be a Ranger-T with bonding flux only applied in the shank, so the petals and "talons" could unfold broadly while still ensuring the jacket stays intact, and internal scoring to produce the lead wedges apparent on the petals of the HST. This of course assumes Winchester can maintain general QC.
Not impressed with R-T, R-B is better AS LONG AS EXPANSION IS CONTROLLED (1.5 caliber ideal, 15.5-16" pen.)