Reversed Bullets


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barnbwt
June 22, 2013, 05:25 PM
I heard tales of these from WWI stories as an attempt at better penetration of thin armor plating by anti-tank riflemen. The bullet (I'm unsure what the construction was of anti-tank bullets in those days. FMJ? :confused:) was seated pointed side in and fired with an increased charge. The theory was that a wider meplat transfers its energy to the target (in the form of shearing a hole) more efficiently than a pointed bullet which delivers a softer impulse to the target as it deforms from the initial point contact.

Rather than ask whether it really works (it's been done to death) I wanted to ask if anyone's tried it. I've become interested in 223 case-head sub-caliber wildcats of late, and my idea was seating a reversed 30 Tokarev FMJ round nose bullet backward.

The case would be an elongated 7.62x25 case with the flat bullet seated flush with the (short) neck. The OAL would match the current x25 OAL. My thinking is the shoulder could be pushed forward by the amount the bullet currently protrudes (quite a large portion of the length of the 7.62x25, btw) and that having the taper, rather than the flat base, inside the case, would not displace as much powder volume.

You'd get another 10-20% of powder volume with no change in envelope (I think). So long as the round remains well above sonic velocities, the stability of the round should not be an issue (the weight is up front so it's actually more stable), and if that speed can be held for a couple hundred yards (which the extra powder should help ensure) the poorer ballistic shape shouldn't drastically effect accuracy either.

Because of the neck-taper of the round, it might still feed as easily as a hollowpoint if the mouth were crimped onto the round even slightly. I suppose that necking the round down further to .25 or even .224 would feed even better, so long as the neck can be kept short. True wad cutters or simple bullets made from brass rod (in rifles only ;D) could be used as well.

We're all aware of the benefits of heavy wad cutter loads from revolvers; why not obtain them for auto loaders?

TCB

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Kernel
June 22, 2013, 08:57 PM
I've shot cheap .30 cal FMJ bullets backwards in low velocity, low noise, plinking rounds in .30-30 & .30-06 with small charges of Unique or Red Dot pistol powders. It's a fairly common practice. For whatever reasons they tend to be more accurate. I've even done it some in .223 Rem, but not to the same extent.

kwg020
June 22, 2013, 09:04 PM
148 grain wad cutters in backward supposedly mushroom real nice even at low velocities. kwg

Jefferson Herb
June 23, 2013, 02:35 AM
Low velocity loads would be more accurate due to weight fwd and slower spin.

hang fire
June 23, 2013, 02:07 PM
The blunt nose projectile for penetration predates firearms. It was found the crossbow bolt with an almost blunt wedge arrowhead penetrated a knight's armor better that a sharp one.

http://www.ancientresource.com/images/medieval_crusades/weapons-medieval/crossbow-bolt-29509b.jpg

http://www.historiavivens1300.at/biblio/beschuss1/bolzen4.jpg

mdi
June 23, 2013, 02:21 PM
I've read this practice was tried during WWI to defeat armor used for machine gun emplacements. Dunno for a fact, but that's what I read...

mdi
June 23, 2013, 02:22 PM
148 grain wad cutters in backward supposedly mushroom real nice even at low velocities. kwg
Inaccurate, tumble, cavity either gets clogged or collapses more often than classic mushrooming. Tried a bit of experimenting myself in the early '80s.

longspurr
June 24, 2013, 12:29 AM
Reversed bullets do good things at short range - however. The O A L of the cartridge may be drastically shortened due to the base of the bullet hitting the forcing cone and causing the bullet to only be 1/8" or so out of the case in order to chamber. This now very short round has much less powder space.

barnbwt
June 24, 2013, 11:45 PM
Here's a diagram of what I attempted to describe initially. Hopefully this better demonstrates the supposed "advantage" I thought a setup like this could possibly achieve. Any impact on penetration or energy transfer would be purely ancillary. The goal is to bump up the capacity in a 7.62x25 envelope (for fitting in existing magazines and bolt faces) in an attempt to get the 30cal bullet up into "light carbine" power levels, as opposed to pistol levels. The lower end of what we consider 30 carbine type rounds (kinda halfway between handgun and rifle rounds).

http://i1159.photobucket.com/albums/p630/barnbwt/TokarevLongWildcat_zps6c4cf437.png

As you can see, the bullet is seated flush, or nearly so, so the forcing cone issue would be a non-issue (they'd contact the leades at the same position). Since the flat point is close to the pronounced shoulder, the shape should still be able to feed about as well as a hollow-point straight-wall case (I think). According to the laws of physics, the pressure in the case would still act on the same net area of the bullet before, so it's not like the energy transfer there would be different. I'm more concerned about what impact the full length of the bullet's contact surface scraping over the case neck will have on it. I'm also curious an FMJ loaded upside down in a high-pressure cartridge is even safe, or if the "guts" would get squeezed out the front. More an issue for lead core than Tok steel core stuff.

For distances where the round remains well above sonic, the shape of the nose actually has very little impact on aerodynamic stability, compared to the benefit of having the center of mass shifted forward. Transonic performance would suck, but that's why the extra powder is used to keep it above water a bit longer. My hope would be good performance out to 200yds (should be easily attainable) since this would be a light carbine round. The Tokarev Long, or Tokarev Magnum, or 300 Zephyr, 300 Brown-Out... whatever :D

TCB

fguffey
June 25, 2013, 12:54 AM
Spalding, in WW1 bullets were pulled from 30/06 ammo, turned around and reseated, the purpose? Snipers used small metal shields that handled small arms fire, but the when the flat end of the bullet hit the metal the opposite side scaled off. Tanks, same thing, it was like hitting an old porcelain stove.

F. Guffey

fguffey
June 25, 2013, 12:57 AM
Then there was a claim it was possible to clean a barrel by reversing the bullet. And I said fantastic.

F. Guffey

barnbwt
June 25, 2013, 01:20 AM
Yup, the broader contact area imparts greater shear force to the steel plate before the bullet splatters. Apparently British tanks could be penetrated on occasion by German riflemen this way. Like I said, though, merely a nice side benefit of what I wonder is a way to increase powder capacity a bit within the same overall length ;)

TCB

jmorris
June 25, 2013, 01:24 AM
It is not rare in subsonic loads out of normally super sonic rounds like the 308 for example to have better results loading the bullets inverted. That is only better results at hitting something.

Not like the very weak loads would cycle a semi anyway...


To go through steel, the best thing I have found is bullets with "hard" stuff in them. Even better if there is hard "stuff" and a driving force in them.

Kind of like these 1" thick steel blocks we shot through with 50 BMG AP and API.

http://i664.photobucket.com/albums/vv5/qvideo/gn/steel1in.jpg

http://i664.photobucket.com/albums/vv5/qvideo/gn/1insteel.jpg

Most FMJ rifle rounds are open base, so the lead core, if it has one, is exposed. There is little reason to assume that the lead core first would have a better ability to penetrate than the harder tip of an FMJ.

jmorris
June 25, 2013, 01:35 AM
Double

twofifty
June 25, 2013, 02:02 AM
I was under the impression, from looking at shot mild steel, that bullet penetration is achieved when enough mass and velocity combine to create heat. The sides of the holes often look like they were vaporized.

Kinda like the work that kinetic anti-tank penetrator rods do.

barnbwt
June 25, 2013, 07:17 PM
Okay, maybe I didn't explain my motivations clearly; penetration is not the goal of this exercise, but increased powder capacity. Does anyone know if reversing an FMJ or HP in full power loads is dangerous? The WWI rounds were, but they were also much higher pressure loads--I would obviously be saner in my formulas.

TCB

PapaG
June 25, 2013, 08:29 PM
I would think that the weight of the bullet and the caliber you are loading for determines how much powder you can use. You want more powder, go to a lighter bullet. Then again, it is your face, hands and gun.

LeonCarr
June 25, 2013, 09:07 PM
There is a great article at www.theboxotruth.com involving a .30-06 with inverted bullets:

http://www.theboxotruth.com/docs/bot32_4.htm

Interesting results.

I once tried loading HBWCs backwards in a .38 Special, calling it the "LeonCarr Conspiracy Load". 2.7 grains of Bullseye with a backwards Speer HBWC, fired at 7 yards from a Ruger SP101. With correctly seated HBWCs, all five would go into one hole at that range. With backward HBWCs, a 5 inch group with 3 of the 5 bullets hitting the paper sideways.

Conventional JHPs are a much better choice for self defense.

Just my .02,
LeonCarr

Kernel
June 26, 2013, 12:20 AM
The 7.62x25 Tok holds 16 grains of water. (For comparison a .223 case holds 31 grains. A 7.62x39 holds 36. A .44 Mag 39). That's overflow capacity. Seat a bullet on your Tok, forward or backward, and you've got around 11 grains (H2O) of space to fill with powder. Not a lot to work with.

The closest thing to it is the .30 Carbine. It holds 21 grains. Studying the .30 Carbine might give you some insights. There's a lot more info out there than the Tok.

The problem before you is how to maximize velocity while keeping pressure within acceptable limits. That’s the “holy grail” all handloaders search for. Reversing bullets, might increase case capacity by some fraction of a grain, but ain’t gonna get you there. Lighter bullets have their trade offs. Your quest is to find that ideal powder that has the pressure-velocity characteristics you seek.

In my view, it’s going to be one of the slower pistol powders. But still a tier below the “magnum” powders like 2400 and H110. I’d be experimenting with powders like HS-7, V-V N105, AA No.9, Blue Dot, and IMR 800x.

Get a chronograph and learn how to read pressure signs. Start low and work up.

barnbwt
June 26, 2013, 08:04 PM
The case holds 16gr at present. With the bullet turned backwards, or simply replaced with a cylindrical so it can be gripped by the neck at the front, the case neck can be moved forward the amount the bullet used to protrude (to get the same crimp engagement). So the case volume would increase a good bit, and the tail of the equal weight bullet sticking further inside would displace a portion of the increase in volume.

"The problem before you is how to maximize velocity while keeping pressure within acceptable limits."
A net increase in the amount of powder that could fill the case, for a round that still has the same overall length. Because volume increases, peak pressure will last longer, and accomplish more energy transfer without additional load on the bolt. x25 maxes around 35ksi, IIRC, and if made from 223 brass, should be capable of comfortably operating up to 223 pressures, if so desired (obviously a locking breech would be required)

If tok is 16gr, and 30 Carbine is 21gr, I imagine my weird little round would be something like 18gr. Just a bump, sort of like an Ackley Improved wildcat, only one where the factory chamber reamer is simply run deeper into the barrel. The x25 has a very large length of bullet protrusion for it's size. I'll have to model it in CAD to see how much actual volume is gained, but it will be a narrow ring of powder around the base of the bullet inside the case. It might have strange burn characteristics that result in soot or a long pressure peak, but it would deliver more power to the bullet.

My main question was whether anyone has heard of any inherent safety issue in trying to seat a bullet past the neck (without increasing powder density, of course). The "reverse bullet" thing was merely the inspiration, and its performance implications obviously a distraction from my inquiry ;). Every wildcat of "typical" layout based on the 223 case head has been done to death already; I kind of figured someone had tried this by now :D

Kernel
June 27, 2013, 01:13 AM
trying to seat a bullet past the neck

Seating depth. No reason you couldn’t seat past the neck/body juncture. If you’ve got enough neck. The old conventional wisdom is a minimum of one caliber deep. So a .30 cal should be seated at least 0.30" deep of bearing surface. There's some wiggle room on that, but I wouldn't push it out to far.

I didn’t gather from your earlier post that you where going to cut a whole new chamber. That opens all kinds of possibilities. I don’t know that you’ll get to 18 grains, but you surly won’t get beyond that.

Why all the effort to reinvent the M1 carbine? What kind of iron you shootin’ there TCB?

barnbwt
June 27, 2013, 09:22 AM
PPSH 41 mags and a locking breech tube gun :D

A huge number of rounds fit and feed from the PPSH mags and drums (7.62, 9mm, 40, 45 with mods, and their wildcats like 9x21, 10mm, 45 Win Mag). As with the others, my hope is that merely stretching the tok case will make for a stouter wildcat like the others, but still use the same case head. 30 carbine is about 1/8" too long, and is so narrow the reverse trick would severely limit powder capacity.

TCB

Robert101
June 28, 2013, 03:06 PM
Ok so I have a limited understanding of pressure dynamics in firearms. My layman's understanding is that there is a close relationship between bullet surface contact area, bullet weight, and bullet diameter that affect the pressure curve. So, if the powder manufacturers have established a max powder charge for a given bullet and its weight, how do you increase that powder charge? I only see the powder charge varying for bullet setback dimensions due to the configuration of the bullet in the case. It seems to me that the final max charge really doesn't net an increase in muzzle velocity. Again, I'm only wondering about the consequences.

Kernel
June 28, 2013, 05:29 PM
^^^
If I understand your question....

The powder charge can increase, without pressure spiking, because the volume of the case is increased due to blowing the shoulder forward, and to a lesser extent, perhaps, by seating the bullet backwards (because by turning it backwards there might be a small increase in internal volume - depending on how it's seated).

TCB, do you have a tube gun in mind? I don't know much about them, but thought they were all medium length bolt actions.

Robert101
June 28, 2013, 06:38 PM
Kernal, yes I do believe your statement characterizes my post. Have a good one.

barnbwt
June 29, 2013, 11:46 PM
The goal is a locking breech gas op tube gun that uses ppsh mags and a quick change barrel. I'm limited by length, but the lockup will be built to handle 10mm or maybe even 45WM (short bullets will fit). It's kind of overkill for Tok as is, except where gentleness on brass is considered.

TCB

stevehenry1
July 7, 2013, 11:43 PM
Spalding, in WW1 bullets were pulled from 30/06 ammo, turned around and reseated, the purpose? Snipers used small metal shields that handled small arms fire, but the when the flat end of the bullet hit the metal the opposite side scaled off. Tanks, same thing, it was like hitting an old porcelain stove.

Guffy, This is what I saw on History Channels' "Digging up the Trenches" The idea was that the scale would get into the snipers eyes, or at least make him more careful while sniping

Kernel
July 13, 2013, 08:17 AM
^^^^

Spalding was a character in the movie Caddyshack. (Or was it Spaulding? What ev. Or a maker of basketballs?)

I think the correct term, in regards to nasty flying metal splinters, is spalling.

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