Doctor Roberts, - (oops, sorry about misspelling your screen name…but dislexics are teople poo!)
Thank you for your work and sharing your knowledge in articles like: “Basic Wound Ballistic Terminal Performance Facts.” Background: the article explains that one of the major differences between “pistol-like wounds” and “rifle-like wounds” is the additional damage caused by the larger temporary cavity from the rifle’s more rapidly traveling bullet. You stated: “tissue that was stretched by the temporary cavity may be injured and is analogous to an area of blunt trauma surrounding the permanent crush cavity.” I noticed an August 1999 “Tactical Briefs” article, that explains that the size and location of the temp cavity can explain the DRT effect (dead right there): where the person or animal collapses immediately and doesn’t move before expiring.(reference below).
My question comes from the vigorous, err, “discussions” on various websites about the “effective range” of various rifle cartridges and their bullets. The cartridges include .223, 6.5mm, 6.8mm, 30blk, 7.62x39, and, for old farts like me, .30 carbine and 30-30. There are claims that some newer rifle bullets reliably expand at lower velocities. Your sticky on the M1 Carbine mentioned the Speer 110 gr .30 carbine gold dot. In addition, I have seen reports about a .30 cal monolithic bullet that is said to expand from about 2400 fps down to 1300 fps. - No high speed photos of the gel tests, however.
At 2300 or 2400 fps, I would think that the bullet would cause “rifle-like” wounds. But what about farther downrange when it has slowed to 1600 fps or to 1300 fps? Has the effectiveness dropped to a pistol-like “crush area only” wound?
Note to flamers: I am not saying that the slower bullets can't be deadly. But slower bullets would cause less damage and would lack the attention-getting oomph that comes from a cantaloupe-or-larger-sized temporary cavity suddenly opening in your chest or thigh.
Based on your experience, at roughly what velocity do the bullets lose rifle-like effects. Is this velocity lower for expanded bullets?
Thanks.
Reference:“Blunt Trauma Concussion of Spinal Cord as Mechanism of Instantaneous Collapse produced by Centerfire Rifle Bullet Wounds to the Torso” : www.firearmstactical.com/briefs28.htm
Not an expert by any means but watching the development of the .300 AAC has been interesting. It seemed initially the round would be hampered by availability of bullets constructed to perform optimally at the velocities generated. Of interest was the Barnes line - long, sleek homogenous copper bullets built for hunting seemed like they would work but were really not optimal because they were built to operate at higher velocities found in the .308, .30-06, .300WM, etc. Luckily the corporate entity behind the .300 AAC were able to have Barnes build them a bullet to work at lower velocities found in the .300 AAC. Bottom line - study your bullets you intend to use and determine if they will work in your velocity ranges.
You make a good point about how different bullets are designed for specific velocity ranges, but I think the OP was asking more about how fast the bullet needs to travel to switch from pistol-like wounding characteristics to rifle-like.
I’m interested as well because The 300 Blackout rounds seem to it between pistol velocites and 5.56 velocities.
Spooky, you are right, but as bzdog noted, I am more interested in the low end of rifle-like velocities.
To provide more context for my question: I have been following intermediate cartridges like the 6.8 SPC since Doctor Roberts first mentioned it on the Tactical Forums website. Now there are more intermediates and yes, bullet companies including Barnes, are tailoring rifle bullets for lower velocity ranges.
Now that more rifle bullets can open up or “upset” at lower velocities, when do they begin to act like pistol bullets? Again, there is no doubt that most intermediate rifle cartridges work well at shorter distances (with the right bullets). Most of the arguments that I see are about effectiveness at longer ranges: 300m, 400m, and in the case of the 6.5 Grendel, considerably longer ranges.
Of course, precise shots that hit the CNS or heart are deadly at long range. The problem is that those precise hits become less and less likely with real world conditions like wind, unknown distances, no spotter shots to zero-in, and less than ideal shooting positions.
On a personal note, I am especially interested in the intermediate cartridges since a serious spine injury has prevented me from shooting for several years. One day, I might be able to shoot an intermediate cartridge, but firing a 300WM would likely result in an ambulance ride for me.
I have read before that the threshold for serious wounds outside of bullet tack to be somewhere around 2000 FPS.
Edit: however DocGKR has said that bullet profile has an effect in it to. As in a .223 that doesn’t yaw will have a much smaller TC than one that does.
I’ll try to find the posts from the folks at Barnes building their new 110 grain TAC-X bullet for the .300AAC. They list a lower end velocity number where that specifically designed bullet stops expanding.
This may not be the exact bullet, but it suggests the 110gr VOR-TX 300BLK should expand down to around 1300-1500fps and actual performance is around 2350fps.
So clearly, the bullet performs well below the velocity of that particular ammunition. And it looks like a really effective bullet and performs at the higher end of 300 BLK velocities due to the light weight (for a 300 BLK).
That said, it isn’t clear if we get the temporary wound channel effect at that velocity or not.
From my investigations and research, Depending on diameter and construction, it appears that the crossover point is somewhere between ~1600 and ~1900. If I had to put a general number on it I’d say around 1700fps for a well designed .30 cal. Higher for a smaller and lower for a larger bullet.
it’s that crossover point that makes the magnum pistol round interesting as they are breaching that threshold with some loads.
is this to say that a 300blk leaving the barrel of an sbr (7.5-10") around 2000 fps would most likely only provide your target with a .30 caliber (with expansion) crush cavity? at that point wouldn’t a pistol caliber (larger in caliber) provide better terminal ballistics on your target? i was under the impression that 300blk ( or other slow riffle caliber fired from an sbr) would provide some enhanced terminal effect over a pistol caliber? is my logic off?
would you say a 300blk (110gr ttsx) fired from a 8" barrel would have better terminal ballistics than say…a .45 acp +p (insert favorite jhp here) fired from a comparable barrel? i only ask this because i am about to go the nfa rout for the first time with an sbr and im torn on what caliber to select.
I cant answer that question for you. that’s something you need to balance and consider cost, ammo, time, effectiveness, bureaucracy, and personal preference.
I would expect the (supersonic) 300 loads to outperform any pistol round.
We haven’t seen the gel shots of that black tip at 300 yards, so it’s hard to say for sure.
The recovered diameter indicates it should make a crush wound at least .585" in diameter.
The black tip does appear to open up down to around 1300 fps.
Well designed defensive handgun ammo opens up within its designed velocity range too.
Recovered expanded diameter and retained weight are clues as to the terminal performance of a round, but the real factor is the amount and depth of tissue damage produced.
Yup,
I was trying to be subtle, but you guys zeroed right in on the round in question. I lost the link, but I believe that both the faster and slower bullets traveled 20 - 24 inches in gel.
This makes me think small temp cavity for the slow bullet, but without a video, it is just a guess.
My understanding is that temp cavities cause energy and speed loss, but “pistol-sized” temp cavities are too small to be a wounding factor.
OK, I forgot about some of the other rounds for lower speeds. It was late at night, sorry about that.
The .30 carbine round from Speer/ATK looks impressive at full velocity. Speer has a good reputation for consistent expansion with its gold dots. I think that the “deep curl” line for rifles uses the same technology.
There are also good bullets for the 6.8 SPC, including the barnes 95 grain round (designed to open up at lower speeds).
I actually have 30-30’s, and wonder about the rounds for them. The pointy FTX bullets from Hornady (and possibly the less pointy speer deep curls) have also increased the effective range of this old round.
In general, the monolithic bullets and the bonded core rounds seem to be more easily tuned to open and present large frontal areas at the lower end of rifle speed ranges.
To me, the big question is “How slow can you go. How slow can you go.” (Sorry about that, but why is limbo music coming from the next room? What the heck is my kid watching on TV?) Got to go.
Well, most of the your 45ACP stuff will have much lower velocity, so even if the 300 BLK gives more pistol like wound cavities, it is doing it at several hundred yards. Up close, where the 45ACP will do its thing, the 300 BLK is traveling above that rifle/pistol wound cavity threshold.
Gentlement, if I may perform a slight thread hijack, I’d like to ask a reverse question. When do pistol rounds speed up enough to act like rifle rounds?
The reason I ask is that I, for some unknown reason, was looking up bullet performance specs and wandered into the .357sig data and noticed a couple of things that made me remember reading this thread.
Now, the 60 gr bullet is some kind of funny “Total Fragmenting Soft Point” which I don’t think applies to this scenario since it probably won’t penetrate deep enough to matter (just a guess here). But the 115 gr bullet is serious business.
Don’t forget the transonic barrier. FYI. Just another thing to worry about. Isn’t this a 200-300 yard effective range at most? I would think the bullets would work fine in that yardage.
