Two-Projectile Loads in Snubby for Self-Defense

[pettypace]

I'm impressed by the penetration that you are getting, even with these light weights, and as slow as 625 fps. If I recall correctly, muzzle loading folk have noted that round balls penetrate further at lower velocities - that is, at short range they penetrate less than at long range, after they have slowed down. Gel tests with black powder pistols show that a short barrel Sheriff's model generating 750 fps will actually penetrate deeper than a long barreled Army at over 1,000 fps. Dead soft round balls do flatten somewhat, so maybe comparing them to hard cast wadcutters is "apples and oranges" - but it would be interesting to know the penetration of identical wadcutters at various velocities. Nice work, thanks for sharing.

Yes. In the Lucky Gunner testing of HP .38 ammo, they test the same ammo from 2" and 4" revolvers. It's not at all uncommon to get more penetration at a lower velocity from the 2" barrel. The explanation there is that the bullets are expanding less at lower velocities and so they penetrate deeper -- very like the flattening of the higher velocity soft lead round balls in the black powder example you cited.

In the case of the two projectile loads, I suspect that the explanation for deeper penetration than predicted is some sort of "drafting" effect.

Some time ago, 35remington suggested gel testing a single light wadcutter at the same velocity as the two projectile loads to see if the equations actually work for a single projectile. That's a good idea. I've just been too lazy to work up single projectile loads that match the velocity of the two projectile loads.

My current "hypothesis" for the extra penetration of the light projectiles in the two projectile loads is that even though they punch two separate wound channels through the gel, for much of their paths, they only create a single temporary cavity. I have no idea how much bullet energy goes into creating the temporary cavity. But the gel is surprisingly tough stuff and there has to be some work involved in creating that cavity. So if two bullets can share that work between them, they'll have more energy left for the productive work of punching a deeper permanent cavity. It makes sense to me. But I don't know how to quantify it or "prove" it.

At any rate, I just realized that I didn't post the temporary cavity pics (such as they are) for all five shots from the last gel test.

[pettypace]

Shot #1:

Attachment 241682

Shot #2:

Attachment 241683

Shot #3:

Attachment 241684

Shot #4:

Attachment 241685

Shot #5:

Attachment 241686

Shot #6:

Attachment 241687

Sorry. That last one wasn't actually a snubby!

[pettypace]

At last Wednesday's Snubbyfest I fired five rounds of my version of the .38 Special Super Police load, rapid fire, into ballistic gel. To my surprise, only one of the five "tumbled" to a stop in the 22" of gel. The other four went through and through. The resulting Super Police video was far less dramatic than the two-projectile video of the previous week and that got me wondering about the likely effectiveness of the two different loads.

It's hard to think about the "stopping power" of handgun ammunition without paying homage to General Hatcher. The good news is that Hatcher has already done the calculation for the Super Police load (Textbook of Revolvers and Pistols, page 435). In fact, he did it twice -- once for the .38 Special Super Police (SP = 36.3) and once for the .38 S&W Super Police (SP = 29.2) -- with the difference being just a question of lower velocity from the .38 S&W. Given that I was shooting a snubby, let's just say that SP=30 for the .38 Super Police load.

Hatcher's stopping power numbers have no absolute meaning -- they are only estimates of relative stopping power. So, how does that SP=30 for an old fashion .38 Super Police load compare to other loads? According to Hatcher, it's about the same as a .38 Super FMJ (SP=31.8), or a 9mm Luger FMJ (SP=29.4), or a standard .38 Special LRN (30.8). Or it's about twice the stopping power of a .380 ACP FMJ (SP=16.2) or about half the stopping power of .45 ACP hardball (SP=60.0).

So, that puts the .38 Super Police load into perspective. But what would Hatcher say about a two-projectile load -- say the two 105 grain wadcutter loads I most recently gel tested? That load has a total mass and velocity about the same as the .38 S&W Super Police load. If the two projectiles didn't separate, I would expect the Hatcher stopping power to be about the same as for the Super Police load, say SP=30 (ignoring a boost for the wadcutter shape). But how would the Hatcher calculation go when the two projectiles do separate?

The problem here is that there are two different ways to think about this and they give much different results: One approach is just to treat each projectile separately. Each projectile has the same velocity and the same cross-sectional area, but only half the mass as the Super Police load. In that case, each projectile would have only half the stopping power and the combined stopping power would just equal the sum of the two. So, we're right back to the Super Police load with SP=30.

But another way to think about it is that the two-projectile load has the same total mass at the same velocity and, so, the same momentum as the Super Police load. But when the projectiles separate, that same momentum now has twice the cross-sectional area. So, we should simply double the cross-sectional area in the Hatcher formula, keeping the mass and velocity the same. So, SP=60 -- the same as GI hardball. And if we factor in Hatcher's 25% boost for the wadcutter shape, we're up to SP=75, or about the same as a 770 ft/s .45 Colt load.

Now, I can already hear some squeals of protest: That there's no free lunch! That there's no way a .38 snubby round has the stopping power of .45 hardball, let alone a .45 Colt. And that it's just mathematical sleight of hand to argue that when two bullets separate and suddenly double their cross-sectional area that they can also maintain their original momentum.

But how would we apply the Hatcher stopping power formula to a JHP that doubles its cross-sectional area by expansion? I doubt many would argue that when the bullet expands, each half of the expanded bullet only gets half the momentum. So the doubling of the area and halving of the momentum cancel out and the stopping power remains the same as it is for the unexpanded bullet.

[35remington]

If I recall correctly Hatcher only applied the formula to a bullet that did not change its shape, because at the time there were no projectiles that reliably did so or at least he did not account for the very few that actually may have existed.

I believe the “manstopper” British bullet of HP shape only got tested in the Thompson-LaGuarde tests of shooting livestock but Hatcher did not follow up with a modification of his formula to account for a bullet that changed its shape after impact.

[pettypace]

OK. But do you see any reason, in principle, that the Hatcher formula shouldn't apply to a two-projectile load? And if not, then how should it apply?

Does each projectile get one-half the stopping power so that the total stopping power is the same as a single projectile load? Or does the total momentum of the load get twice the cross-sectional area so that the stopping power of the load is doubled?

I don't believe Hatcher's formula is the best way to analyze "stopping power." But for those who like the Hatcher formula, this seems like a question worth considering.

[Bill*B]

Keith in his book "Sixguns" reported that old civil war vets, who were in the thick of heavy fighting, had only praise for the effect of their revolver-fired round lead balls. Our current formulas would consider these to be pretty anemic - so there must be more to it than we know.

Here's a theory - now, I most freely admit that I do not know - but let your mind float free (a stiff shot of whiskey might assist) and follow these thoughts:
1. No handgun with less power than a full house .357 Magnum delivers any significant "shock effect" - that is: when a bullet impacts with less than 600 ft/lbs of energy, it does its work by penetration alone.
2. For anti-personnel use, any loads less than 600 ft/lbs that penetrate at least 12" are equal - that is, bullet weight does not matter. A light bullet penetrating 12" punches the same diameter hole as a heavy one that can go 36". Both go all the way through - the superior energy and penetration of the heavy bullet is wasted (we aren't taking heavy game).
3. A .45 ACP slug has a frontal area of 0.16 square inches, while a .38 slug has a frontal area of 0.10 square inches. Therefore, two .38 slugs (that total 0.20 square inches of area) are slightly superior.
4. Your J frame, firing the old Remington dual ball load, outguns the grand old Army 1911 loaded with hardball.

Let the flames begin! Seriously, has anyone actually shot anything with a dual ball load? Field experience always trumps theory. I don't have any, but I would like to hear yours.

[35remington]

I suppose in this theoretical exercise it might be relevant to account for the divergent paths of the projectiles. To what extent do they diverge, and how does that change with distance? If both go nearly through the same hole, does that invalidate the effect of the second bullet’s shape if the first bullet creates a cavity that allows free flight for the second without enlarging the hole?

One would expect that the attenuation of velocity upon impact would slow the first bullet significantly. The second bullet would catch up so to speak and they would tend to penetrate together, possibly accounting for the associative effect that lets them penetrate more than the predictions say they will.

And yeah, Hatcher’s outdated formula is still just that, but I don’t see why it wouldn’t apply. The thing to figure is how much of it applies via how much flesh is exposed to the bullets as they penetrate. What do the wound tracks in the gel show as far as divergence?

[pettypace]

Here's a theory - now, I most freely admit that I do not know - but let your mind float free (a stiff shot of whiskey might assist) and follow these thoughts:
1. No handgun with less power than a full house .357 Magnum delivers any significant "shock effect" - that is: when a bullet impacts with less than 600 ft/lbs of energy, it does its work by penetration alone.

Here are a couple Fackler wound profiles that may help illustrate this point. The temporary cavity from the .357 is about 4" in diameter -- maybe big enough to start doing some permanent tissue damage beyond what the bullet actually hits.

Attachment 241919

By contrast, much of the .45 hardball permanent cavity is likely to be through thin air.

Attachment 241920

[pettypace]

What do the wound tracks in the gel show as far as divergence?

35remington: Here are a couple still shots from the video of the two 105 grain WC gel test. The gel blocks are ammo can size -- 11" long.

In the picture below, the gel is just starting to settle down after the first shot. Both bullets made separate entrance holes, about 3/8" apart, and separate, nearly parallel paths through the gel until they started to diverge at 7" to 8". For this shot, the top bullet went TNT (through and through).

Attachment 241921

In the frame below the gel has just settled down after the second shot. Here, too, there were separate entrance holes and two nearly parallel paths. But in this case the paths diverged after only about 5" and total penetration for both projectiles was less than for the first shot.

Attachment 241926

After the second shot, the gel got pretty busy and it's hard to find a frame that shows the bullet paths. But the frame below shows the fifth shot before the temporary cavity collapsed. Looks like the paths began to diverge at about 7".

Attachment 241932

[ofitg]

Keith in his book "Sixguns" reported that old civil war vets, who were in the thick of heavy fighting, had only praise for the effect of their revolver-fired round lead balls. Our current formulas would consider these to be pretty anemic - so there must be more to it than we know.

The performance of those Civil War revolver loads was comparable to some modern cartridges - in the comparison below, it's interesting to note that the .357 generated more than twice the energy of the old cap & ball revolver -

- - - - - - - - - - - - - - - - - - - -

From HANDGUNS magazine, Ed Sanow, Feb 1998 -

.44 lead ball (percussion revolver), 141 grains, velocity 840 fps

Gelatin penetration 20.5 inches
Recovered diameter 0.48 inches
Stretch cavity 35.2 cubic inches

- - - - - - - - - - - - - - - - - - -

From STREET STOPPERS, Marshall & Sanow, 1996 -

.357 Mag, Remington 158 gr SJHP, velocity 1235 fps

Gelatin penetration 19.0 inches
Recovered diameter 0.50 inches
Stretch cavity 35.2 cubic inches

[35remington]

I now suppose it would be a good time to compare to a single bullet of identical weight as the double load uses to account for what amounts to impact cavity overlap.

The question to try to answer is whether the double load creates double the wound volume of a single bullet, or somewhat less than that due to their proximity as they penetrate. If the double load penetrates further than a single bullet of the same weight that would seem to indicate something along that line of thought. Just what it is indicating is the debatable part.

For instance, more penetration may offset the amount of wound cavity overlap that occurs, and damage may approach 2x that of a single equivalent weight equivalent velocity individual bullet.

But then we are actually comparing a double load to an equivalent velocity or perhaps higher velocity load using a single bullet of equal or maybe lesser total weight. That stickies the wicket a bit in terms of defining outcomes versus alternatives.

[Michael J. Spangler]

The performance of those Civil War revolver loads was comparable to some modern cartridges - in the comparison below, it's interesting to note that the .357 generated more than twice the energy of the old cap & ball revolver -

- - - - - - - - - - - - - - - - - - - -

From HANDGUNS magazine, Ed Sanow, Feb 1998 -

.44 lead ball (percussion revolver), 141 grains, velocity 840 fps

Gelatin penetration 20.5 inches
Recovered diameter 0.48 inches
Stretch cavity 35.2 cubic inches

- - - - - - - - - - - - - - - - - - -

From STREET STOPPERS, Marshall & Sanow, 1996 -

.357 Mag, Remington 158 gr SJHP, velocity 1235 fps

Gelatin penetration 19.0 inches
Recovered diameter 0.50 inches
Stretch cavity 35.2 cubic inches

Aren’t Marshal and Sanow kind of a bunch of hype backed by assumptions?

[ofitg]

Aren’t Marshal and Sanow kind of a bunch of hype backed by assumptions?

I would say that their "Stopping Power" evaluations were dubious..... but they were pretty good at conducting gelatin tests.

[Bill*B]

I admit that I have trouble visualizing that a couple of dinky little 358" round balls could create more havoc than a heavy 160 grain flat point does. On the other hand, (again, apples and oranges, but for the benefit of discussion) the original Viet Nam conflict 5.56mm rifle round was designed to yaw 90 degrees on impact, break in half, and send two projectiles in divergent directions. By all reports, it was devastating in its terminal effect. Years before, British ordinance engineered their MK VII .303 bullet to do exactly the same thing - immediately yaw, and break in half. Only when that was perfected did they give up their infamous "Dum Dum" hollow points. Maybe we should look at a multi projectile load as the near equivalent of a single projectile that immediately breaks in half on impact.

[Michael J. Spangler]

I admit that I have trouble visualizing that a couple of dinky little 358" round balls could create more havoc than a heavy 160 grain flat point does. On the other hand, (again, apples and oranges, but for the benefit of discussion) the original Viet Nam conflict 5.56mm rifle round was designed to yaw 90 degrees on impact, break in half, and send two projectiles in divergent directions. By all reports, it was devastating in its terminal effect. Years before, British ordinance engineered their MK VII .303 bullet to do exactly the same thing - immediately yaw, and break in half. Only when that was perfected did they give up their infamous "Dum Dum" hollow points. Maybe we should look at a multi projectile load as the near equivalent of a single projectile that immediately breaks in half on impact.

That’s a very good way to look at it.

[Bill*B]

This thread started out as "two projectile loads for self defense". It is such fun to roll theoretical concepts around in our brains that we often suppress some inconvenient truths. If an attacker is just interested in plunder, the mere show of any firearm - even a .22 short - will likely break off an attack. On the other hand, if you are facing a charging nut case at close range who really, really, really, wants you dead - then only a CNS hit can provide any hope of salvation. Again, even a .22 short will suffice. Please don't take this as criticism. I got wrapped up in this enough to load up a couple of cylinder full of double ball loads, and plan to test them at the range tomorrow. BUT - should the **** - what I have in the little pistol doesn't matter so much as DO I HAVE THE PISTOL.

[3leggedturtle]

FWIW, out of my LCR a ..375 round ball swaged down to .359 and loaded on top of 3grs Bullseye went thru a treated 2x8, 3/4's of the way. A 158gr FP also loaded with 3grs Bullseye went thru the 1st board and 3/4's the way through the 2nd board. Neither deformed at all. Both were cast with 50-50 WW and pure lead.

[Bill*B]

Pettypace piqued my interest (darn it!), so I located an old Ideal .358" round ball mold, and cast a couple of dozen balls. These were loaded over 3.0 grains of Bullseye: a deep seated ball, then a wax "wad" (of dental baseplate wax pressed into the case mouth by my thumb - hopefully just to provide some lubrication) followed by a second ball which was seated firmly against the first, and held into position by a stout roll crimp. These hard cast - about BHN 15 - balls weighted 66 grains each. Run through a .358" sizer, they were too loose to suit me, so I seated them as cast, which gave a very snug fit into the case. All firing was at 10 yards. A couple of individual shots showed the balls impacting 1 3/4" apart. I then ran a cylinder full through my airweight J frame for a 6 3/4" wide by 4" high pattern. The print of ten balls clustered together was impressive! A composite target including the first two shots measured 6 3/4" wide by 5" high, centered but 3 1/2" below point of aim. Putting this into easily visualized context, if I had a 8 1/2 by 11" sheet of typing paper in my sights at 30 feet, 13 of the 14 balls would have struck it, all in the bottom half, with the outlier 1/2" low. **** for target shooting, but quite interesting in a defensive context. There may be something to these multi-projectile loads, after all.

[pettypace]

Pettypace piqued my interest (darn it!), so I located an old Ideal .358" round ball mold, and cast a couple of dozen balls. These were loaded over 3.0 grains of Bullseye: a deep seated ball, then a wax "wad" (of dental baseplate wax pressed into the case mouth by my thumb - hopefully just to provide some lubrication) followed by a second ball which was seated firmly against the first, and held into position by a stout roll crimp. These hard cast - about BHN 15 - balls weighted 66 grains each. Run through a .358" sizer, they were too loose to suit me, so I seated them as cast, which gave a very snug fit into the case. All firing was at 10 yards. A couple of individual shots showed the balls impacting 1 3/4" apart. I then ran a cylinder full through my airweight J frame for a 6 3/4" wide by 4" high pattern. The print of ten balls clustered together was impressive! A composite target including the first two shots measured 6 3/4" wide by 5" high, centered but 3 1/2" below point of aim. Putting this into easily visualized context, if I had a 8 1/2 by 11" sheet of typing paper in my sights at 30 feet, 13 of the 14 balls would have struck it, all in the bottom half, with the outlier 1/2" low. **** for target shooting, but quite interesting in a defensive context. There may be something to these multi-projectile loads, after all.

What about penetration? Maybe you were getting close to 700 ft/s from the snubby? Here's the Schwartz calculation for a 66 grain, .36 caliber round ball at 700 ft/s:

700^0.745*66/7000/(0.36/2)^2/3.14

Copy and paste that mess into a google search and you should get an answer just over the FBI 12" minimum.

[Bill*B]

I'm shooting on a public range, and have no way to measure penetration. I expect that your velocity estimate and penetration calculation are both about right. The grouping would likely have been tighter if I were a better shot. With single bullets I average around 4 or 5 inches with the little J frame at that distance.