I'm realizing that I'd been misunderstanding the frangible rounds that Foxfire has suggested the CO Shooter might be using. He'd given them a decent introduction, but I've only just putting some of it together for myself. I'm sure I'm oversimplifying, but let me know if I'm badly misunderstanding any of this, Foxfire, please.
Different kinds of bullets behave differently when they move thru things, and they leave different remains.
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Solid bullets pass thru most things (including a tempered glass car window and flesh) in a generally straight line. They remain in one piece and in close to their original form.
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Hollow pointed bullets. A hollow pointed bullet blossoms into a mushroom shape, when it starts to hit a soft target like flesh. Normal hollow pointed bullets may cast off small bits of themselves in a soft target, but one big piece remains. The screenshot below is of a block of gel into which test shots have been fired. The topmost test (B) was of a hollow point bullet. You can see the mashed bullet at rest in the gel.
View attachment 76307
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Frangible bullets. These are designed to come apart inside their target to deliver their energy quickly to the target. There are a number of different designs. Some only leave a remainder of metal dust, but some also leave metal bases and jackets.
http://www.potomacltd.com/images/full2rletterweb.jpg
---- (E) is the "9mm Extreme Shot EPR" frangible round. The gel is mushy to the touch, but quite hard to a bullet impacting it at above the speed of sound. The force of the impact breaks the bullet up, and within a couple of inches of flight, the resulting bits are starting to diverge. Small pieces, from the crumbled core of the bullet, peter out first. Larger pieces (the bullet's metal base and sidewall casing) travel further before they stop.
---- (D), the fourth line down, is for the "9mm Extreme Shot AFR". It's core fragmented into a range of size particles. The same round is reported to move thru hard barriers like sheet metal or glass without disintegrating, and is only supposed to disintegrate if hits soft material or a solid wall of something hard.
---- Another design consists of an unsheathed core, and thus leaves no base or casing material behind. Foxfire has a picture, which I 'quote' at the top of this post, of a gel test of unjacketed frangible ammunition made by IMC. It goes a long way thru the gel before breaking up.
Assuming I got that all right, it makes Cori Romero's wound seem consistent with a hit from a frangible round. The round hits her obliquely (and thus with less impact than head on, as in the gel tests) and has only partially broken apart by the time it exits her neck, with only one small spurt of material diverging in the path I noted earlier just above the main exit wound.