5.56 for defense in short barrel

[NKBJ]

Shhhh! That's science instead of internet.



That may have been what the men's gun rags stated at the time, but that's not how the eventual M16A2 platform worked out. The 1:7" NATO twist is far from 'barely adequate', and is fully 100% tighter than the original XM16E1s shipped.

NO elongated bullet going through ballistic transition into as dense a medium as a human torso will remain dynamically stable through that transition. Catastrophic yaw results from over-turning moment of intertia being drastically increased on the meplat. No amount of rigidity of the rotational axis is enough to prevent this, and the ass end tries to become the front.

Solid bullets can handle it, and some heavier jackets can,..."match" bullets, by their very nature for consistency in target shooting, have thin jackets. Going into yaw, the jacket on the 77 MatchKing's long axis ('cannelured' or not) does NOT have the strength to tolerate the force imparted, and it shreds. Berger's are worse.

The lethality has ZERO percent to do with any "hollowpoint", which is why it is not applicable to Hague, or any other convention, and is in common use in combat. Same for the 175 SMK and 190 SMK in common use in the .308 and .300 WM rifles. That they shred pretty badly is not worse than some Hague-constrained 7.62x39 open-base ammunition whose bullet yaws in the same fashion, and whose jacket holds 'integrity', but crushes like a pop can and sprays lead out the bottom...

...but as avboiler questions, I ask "Why not have both?!"

65 GameKing @ 3,000.

-Nate

Gun rags?
One in seven came along later. The evolution of the changes wrought is an interesting subject.

 

[rhino]

I chose the Black Hills 5.56 with a 50 gr Barnes TSX. Still has good results from a 10.5" barrel. Basically barrier blind as well.

Possibly still does its job in shorter barrels, but I haven't been able to safely suppress say a 7" so I have not delved into close range ballistics from anything under the 10.5"

Just curious . . . how do you determine "good results"? Are you talking about poking through glass and plywood, or terminal effects?

Is that the same or similar copper bullet that Cor-Bon used in its DPX ammo? I forgot to mention the 62gr Cor-Bon DPX. That's probably best choices if you need to poke through stuff and still do a good job on tissur.

Shhhh! That's science instead of internet.

Damn! I did it again. I should be ashamed.

That may have been what the men's gun rags stated at the time, but that's not how the eventual M16A2 platform worked out. The 1:7" NATO twist is far from 'barely adequate', and is fully 100% tighter than the original XM16E1s shipped.

NO elongated bullet going through ballistic transition into as dense a medium as a human torso will remain dynamically stable through that transition. Catastrophic yaw results from over-turning moment of intertia being drastically increased on the meplat. No amount of rigidity of the rotational axis is enough to prevent this, and the ass end tries to become the front.

Solid bullets can handle it, and some heavier jackets can,..."match" bullets, by their very nature for consistency in target shooting, have thin jackets. Going into yaw, the jacket on the 77 MatchKing's long axis ('cannelured' or not) does NOT have the strength to tolerate the force imparted, and it shreds. Berger's are worse.

The lethality has ZERO percent to do with any "hollowpoint", which is why it is not applicable to Hague, or any other convention, and is in common use in combat. Same for the 175 SMK and 190 SMK in common use in the .308 and .300 WM rifles. That they shred pretty badly is not worse than some Hague-constrained 7.62x39 open-base ammunition whose bullet yaws in the same fashion, and whose jacket holds 'integrity', but crushes like a pop can and sprays lead out the bottom...

...but as avboiler questions, I ask "Why not have both?!"

65 GameKing @ 3,000.

-Nate

Does anyone commericoally load the 65gr GameKing?

I suppose my point is, with a Mk262 Mod 0 clone (77gr Nosler CC) at nominal 18" 5.56 Mk262 velocity, a shot through the top of a deer's skull at 65yd and traveled 10" through brain, spine and neck muscle yet did show any obvious signs of fragmentation. The bullet clearly yawed and created an impressive wound, and the animal was very cleanly harvested with surprisingly impressive (to me) terminal effects. If 22 centerfires were legal in Indiana as they are in Kentucky, I'd absolutely not hesitate to use a Mk262 clone on deer given my personal experience.

However...

A 10.5" 5.56 shooting that same load is going to be moving 400fps slower, and obviously the decreased velocity will have a downside impact on fragmentation; will it also have a downside impact on bullet upset/yaw and therefore wound channel? My own research has been inconclusive, though again I acknowledge Mk18s loaded with Mk262 have proven plenty effective in combat over the last decade-plus. I suppose my concern would be with the long wound neck observed with Mk262 even at 18-20" velocity and how that would be amplified from a short barrel - something like a 5.56 pressure 77gr TMK (vs. SMK) would negate that potential concern over neck length.

It seems to me that, having the choice, using a bullet you KNOW will expand to double diameter at your weapon system's muzzle/impact velocity is a better option than a bullet you can't be sure will produce yaw and/or fragmentation terminal effects. Obviously YMMV, caveat emptor, etc....and God knows I wouldn't volunteer to be shot by any of the discussed bullets.

Good technical discussion!

That's a reasonable line of thinking. I suppose that's why we have to define our performance criteria. Keep in mind that while fragmentation is never guaranteed, neither is expansion of bullets designed to expand. Sometimes they just don't. The rotation of a long, narrow projectile when it enters gooey stuff is very, very likely. Even if it doesn't fragment, it's going to tear a slot the the width of the bullet's length by the thickness of the bullet, with is going to be a big hole. The only problem you might have is if the target is too thin for the bullet to yaw sufficiently before it exits.

Gun rags?
One in seven came along later. The evolution of the changes wrought is an interesting subject.

So did the longer bullets (like the 62 gr M855/SS109 projectile, for which the 1:7 twist was implemented.

The M16 and M16A1's 1:12 twist is plenty fast to fully stabilize the shorter 55gr M193 projectile and anything shorter than it.

 

[natdscott]

Gun rags?
One in seven came along later.

Yes. Gun rags. Guns & Ammo, American Rifleman, Field & Stream, blah blah blah....you know, the ones with more advertising and/or political steam than they have actual facts? There are exceptions, but a majority are full of bullsh@# composition by bullsh@# authors.

I am aware of the history of the M16 platform; more important, I am fairly aware of what it has been able to BECOME, and that is what is up for discussion here.

Does anyone commericoally load the 65gr GameKing?

Unfortunately no, not that I am aware of. HSM has a BUNCH of unconventional .223 and 5.56x45 loads though, including a Winchester 64...but I'm not experienced with that bullet, so I can't speak for it.

More reason to handload!

-Nate

 

[rhino]

Unfortunately no, not that I am aware of. HSM has a BUNCH of unconventional .223 and 5.56x45 loads though, including a Winchester 64...but I'm not experienced with that bullet, so I can't speak for it.

More reason to handload!

-Nate

I'm too lazy.

I keep M193 for my rifles in the event of any unavoidable tense social encounters.

 

[dudley0]

Just curious . . . how do you determine "good results"? Are you talking about poking through glass and plywood, or terminal effects?

Still does what it is supposed to with the loss of velocity the 10.5 gives it. Not a distance round by any means, but we were talking HD so close in shooting. I think that the round will still do what it was designed to out to the 100 yard mark, which is more than I would need for sure.

This is a barrier blind load, so popping holes through intermediate barriers like auto glass, walls and such still lets it go thru to the softer targets. Obviously I have not tested this myself, but have relied on testing from others such as Doctor Roberts. Also from what I have read this bullet is designed to be proprietary for the BH round. They sell a 50 gr TSX for reloading but it isn't the same.

All info from maybe a year and a half ago... so I guess it could have all changed by now.

 

[Excalibur]

So the real question is. Should one use a short barrel AR for defense at all compared to a longer barrel? Would a short barrel AR be better for HD if you plan to use a rifle, which a lot of people do.

From reading around, a heavier bullet and a heavier buffer works better

 

[hemicharger]

I'm too lazy.

I keep M193 for my rifles in the event of any unavoidable tense social encounters.

Glad I'm not the only person who uses M193.

 

[avboiler11]

So the real question is. Should one use a short barrel AR for defense at all compared to a longer barrel?

Yes; there are times shorter barrels are more optimal (maneuvering, vehicle ingress/egress) than longer barrels and honest-to-goodness home defense is one of those scenarios.

Would a short barrel AR be better for HD if you plan to use a rifle, which a lot of people do.

Short barrel is just fine, but you need to match your ammunition to your weapon system and use.

Generally speaking, bullets need velocity to be effective on target, be it via expanding or yawing/fragmenting. Fragmentation generally requires more velocity than tumbling or expansion. A typical 10.5" SBR doesn't maintain fragmentation velocity with M193 or M855 very far, and Mk262 was found to be far more effective at lower velocities due to yaw/tumbling. Another way to ensure sufficient velocity for a bullet to be effective terminally is to use a lighter bullet...and many modern expanding bullets (50/55gr Hornady GMX, 62gr Federal Fusion, 64gr Nosler BSB, 55/64gr Gold Dot, etc) available to non-Hague users provide plenty of velocity to ensure significant expansion.

 

[rhino]

So the real question is. Should one use a short barrel AR for defense at all compared to a longer barrel? Would a short barrel AR be better for HD if you plan to use a rifle, which a lot of people do.

From reading around, a heavier bullet and a heavier buffer works better

I say yes if you don't expect to need to take shots at longer distances. You just have to understand the limitations and choose ammo accordingly. A short barreled AR is way faster to drive onto target and between targets than 14.5, 16, 18, or 20 inch rifle. The closer your contact, the more speed matters. Shorter weapons are also easier to maneuver in tight places.

Glad I'm not the only person who uses M193.

It's got a good track record on both people and pigs. From a 16 inch barrel (which is what I have), I can expect reliable fragmentation to around 200 yards, which is longer than I am ever likely to shoot for defense. It's not going to penetrate through glass or car doors as well as a bonded jacketed soft point, which I accept. No 5.56 bullet is going to do that well penetrating hard stuff compared a man's cartridge like a .308, so in my opinion it's just a matter of which sucks less at penetrating intermediate barrier.

My old 3-gun rifle (a 16 inch Colt) is zeroed for 68gr Black Hills OTM. Back in the 90s the ammo was cheap and I still have a few boxes. If I had to shoot a little past 200, it would do the trick better than the M193 and it's significantly more accurate.

If and when I do an SBR, I'll have to rethink my choices.

 

[Excalibur]

That's pretty much the whole purpose of building my AR short barrel for practical purposes and understanding that if used, it'll most likely be used in close quarters and short ranges. A short barrel AR is very compact for storage in a car for the on the go person.

 

[SSGSAD]

I've never really bought into the "defensive" rounds bc of their price. I know the test show more damage but I'm still in favor of using what you train with. Also, I don't know if you will get much expansion in a close quarters situation with a rifle. I may be wrong tho. Go with what you can afford and keep training with it.

The only comment, I can make, is

3000 fps, is 3000 fps .....

I have "always been told", that a FMJ, RIFLE bullet, will OVERPENETRATE .....

and, a hollow point, 223, will not penetrate a human body .....

I have no proof, or evidence,

Just what I have been told .....

 

[NKBJ]

Yes. Gun rags. Guns & Ammo, American Rifleman, Field & Stream, blah blah blah....you know, the ones with more advertising and/or political steam than they have actual facts? There are exceptions, but a majority are full of bullsh@# composition by bullsh@# authors.

I am aware of the history of the M16 platform; more important, I am fairly aware of what it has been able to BECOME, and that is what is up for discussion here.



Unfortunately no, not that I am aware of. HSM has a BUNCH of unconventional .223 and 5.56x45 loads though, including a Winchester 64...but I'm not experienced with that bullet, so I can't speak for it.

More reason to handload!

-Nate

So your assumption is that what I was reading in the 1960's was a "gun rag".
Ooookay.

 

[NKBJ]

That's pretty much the whole purpose of building my AR short barrel for practical purposes and understanding that if used, it'll most likely be used in close quarters and short ranges. A short barrel AR is very compact for storage in a car for the on the go person.

What ranges are you going to design your defensive load around? This is interesting.
The original idea of turning a .22 projectile into an energy dump three times that size via rotation is pretty neat.

 

[natdscott]

So your assumption is that what I was reading in the 1960's was a "gun rag".
Ooookay.

No, because I don't really care what you read now, much less what you read then.

But if that's what was being said, then it was rag material then, as it would be now.

-Nate

 

[M67]

So, what was decided on this? 5.56/223 sucks and 375H&H is needed? Or was it 5.56 sucks out of a 10.5" barrel but 9mm RIP out of a 4" barrel could kill an elephant?

 

[dudley0]

So, what was decided on this? 5.56/223 sucks and 375H&H is needed? Or was it 5.56 sucks out of a 10.5" barrel but 9mm RIP out of a 4" barrel could kill an elephant?

Why waste all that maneuverability with a 4" barrel when RIP out of a 3" will still kill anything alive today?

 

[M67]

Why waste all that maneuverability with a 4" barrel when RIP out of a 3" will still kill anything alive today?

True, forgot that RIP out of a 3" will make the damage look like a 6" all day every day

 

[rhino]

Fellas! Fellas . . .

. . . don't you know that size doesn't matter?

 

[Excalibur]

What about Hornady Black?

 

[JAL]

Why waste all that maneuverability with a 4" barrel when RIP out of a 3" will still kill anything alive today?

A Ruger Alaskan with 2.5" barrel is even better, chambered in .454 Casull or .480 Ruger, take your pick. Don't believe the specific cartridge makes much difference with those, but the Hornady XTP HP are quite well regarded. The forensics team might have to go two doors down to recover the slugs though.

John