Request for info: wounding mechanisms in fragmenting vs. soft-point .223/5.56 loads

[TriumphRat675]

I typically am not overly concerned with the differences in various loads or brands of ammo - get something on the recommended list and practice a lot instead of worrying about what is "best" seems like the best use of my time. Having said that, I would like to know something about the different wounding mechanisms in different types of rifle loads, just to broaden my knowledge base. I went through the stickies and did not find this info; if it's contained somewhere else please let me know.

My very basic and possibly incorrect understanding of fragmenting bullet designs is that the fast-moving bullet sets up a temporary cavity; the bullet, once it fragments, creates tears and other trauma in the temporary cavity rendering it something akin to a large permanent cavity.

My very basic and possibly incorrect understanding of the non-fragmenting soft-point bullet designs, like the Speer Gold-Dot, is that they expand, retain weight, and penetrate better than a fragmenting design. It seems to logically follow that the expansion will create a larger permanent wound channel, and perhaps a slightly larger temporary cavity, but without the fragments causing tears and additional trauma to the large temporary cavity that a fragmenting design would have, and therefore less effective at stopping aggressive behavior in a timely manner.

If the above is correct, for a civilian whose only likely use of a carbine is in a self-defense scenario and who is not as concerned with defeating intermediate barriers as a LEO might be, wouldn't a round that reliably fragments through a range of velocities be a better choice than a soft-point or expanding round? If my thinking and/or information is wrong, I'd appreciate getting correct information.

[DocGKR]

You seem to have an excellent grasp on the topic. Both types of projectiles will work on unobstructed targets. The more robust barrier blind loads also work when intermediate barriers are present. They also are better if you need to punch through a large bone, like when someone has a firearm pointed at you and your projectile must first get through the arm before reaching the head or torso.

[TriumphRat675]

Ok, so all else being equal, for the reasons you mentioned a civvie in an HD scenario is probably better served with an expanding, barrier blind round over a fragmenting one, even if the fragmenting one may have slightly better terminal effects on unobstructed targets. Groovy.

Doc, thank you for the response.

[Wiggity]

You seem to have an excellent grasp on the topic. Both types of projectiles will work on unobstructed targets. The more robust barrier blind loads also work when intermediate barriers are present. They also are better if you need to punch through a large bone, like when someone has a firearm pointed at you and your projectile must first get through the arm before reaching the head or torso.

Just something to consider...an arm in the way of the head/torso could easily be negated by the fact that you will be firing multiple shots at the target until it is no longer a threat.

[TriumphRat675]

Just something to consider...an arm in the way of the head/torso could easily be negated by the fact that you will be firing multiple shots at the target until it is no longer a threat.

Sure, unless, for whatever reason you are able to take one, or only one accurate, shot at the target. It's not hard to think up a scenario where that might be the case, especially in the type of situation Doc brought up. What percentage of wounds suffered in gunfights are to the hands and arms? IIRC it's surprisingly high.

Good example is the 1986 shootout - Platt, I think, was hit by a pistol round that penetrated through his arm and into the torso before stopping an inch from his heart. The agents didn't a chance to make another shot like that for a while. They would have been better served with a better-penetrating bullet.

I think Doc's point is, all else being equal, when you have a choice between a round that may have marginally better wounding capacity vs. one with superior barrier penetration, the better option would be to sacrifice the marginally better wounding capacity for the increased ability to defeat barriers, even in a civvie context. But at this point I'm way out of my lane and onto the shoulder...

[200RNL]

Good example is the 1986 shootout - Platt, I think, was hit by a pistol round that penetrated through his arm and into the torso before stopping an inch from his heart. The agents didn't a chance to make another shot like that for a while. They would have been better served with a better-penetrating bullet.

Yes, a FMJ would have been more effective in that particular case.

[Leatherneck556]

Originally posted in the thread about recent rifle round testing:

Also note the size of the recovered Mk318 OTM projectiles--they truly do not compare with an expanding LE style bonded JSP like the TBBC or the .30 cal VMAX.

Given the dynamic discussed in this thread (fragmentation creating a theoretically more severe wound in an unobstructed target vs. expansion/penetration being more "guaranteed"), where does the Mk318 fall out? I know that it's recommended in your 5.56 Duty Loads thread, but it seems like its reception is lukewarm. To a layperson like myself, it seems like this projectile would provide the best of both worlds: fragmentation that makes a much more severe wound out of the temporary cavity and deep penetration needed to reach vitals through obstructions. Why is it that this particular round isn't considered as effective as the bonded JSP rounds?

My best guess is that it may theoretically work better than bonded JSP in unobstructed shots, but that it's like TSX when passing through auto glass: the front end fragments before it ever hits the intended target and it ends up essentially acting as a .22 caliber "wadcutter" that passes through its target only making a .22" cylindrical permanent cavity.

Doc, could you give some more clarity on this topic?

[DocGKR]

Take a look at how much smaller the recovered Mk318 projectile is compared to the 5.56 mm bonded barrier blind loads--guess which ones crush more tissue? Recall that the optimum penetration depth is 12-18", which projectiles fall into that range--Mk318 or bonded barrier blind loads?

[Leatherneck556]

Sir, I understand that the recovered diameter is smaller and that the solid copper shank of the Mk318 crushes less tissue than one of the bonded JSP rounds, but the question I'm asking is really about fragmentation.

My understanding is that the non-bonded lead core of the Mk318 fragments upon impact and exhibits the same characteristics as other fragmenting rounds like was discussed in the original post of this thread. Is that not the case? If it is the case, then wouldn't the temporary cavity that results from a Mk318 wound be shredded by the fragments and in turn be much more severe than the recovered diameter would otherwise indicate?

[DocGKR]

The nose of the Mk318 fragments--this can enhance damage caused by the TC due to the fragments from the Mk318 nose portion first weakening tissue in the early part of the wound track. Likewise, a larger projectile expanded diameter from a bonded JSP also increases the temporary size, thus disrupting more tissue, as well as continuing to crush more tissue throughout the full length of the wound track. Both mechanisms increase tissue damage and I am unaware of any data to suggest which method is more effective at causing a threat to rapidly cease hostilities.