.38 double wadcutter load

[El Cid]

I’m amazed you’re still trying to convince anyone a duplex load is viable. Maybe if we are getting overrun by waves of Chi-com soldiers I’d fancy a round that gives multiple hits with one press of the trigger. But it would have to be more substantial than anything out of a handgun. Never mind a 38spl. Maybe some grape shot rounds out of a 105 howitzer that’s parallel to the deck.

But for private citizens and LE, we need to know exactly where our rounds will impact. Precision > * Even if you’re ammo idea had the terminal ballistics to properly stop a bad guy (it doesn’t), it would still lack the precision required for us to safely employ it.

[the Schwartz]

Here's another blast from the past: The original Webley Manstopper with two multi-projectile "modern manstoppers" circa 1935. From a sketch by Hatcher in Textbook of Pistols and Revolvers, page 361.

Attachment 46676

Since this is a technical forum where all aspects of ammunition design, effectiveness, and its terminal performance—and yes, even historical material—is discussed, I'd like to thank you for what you've done so far: open a discussion about a topic that, while it may not be the success that you'd hoped, offers anyone willing to look the possibility to learn something new. Not having a copy of Hatcher's Textbook of Pistols and Revolvers of my own, I appreciate what you have provided; I was unaware of it. Thanks.

[SiriusBlunder]

I accept Schwartz's expedient equation will predict penetration in BG +/- .39 inches with 95% confidence.

Let's look at the actual testing & prediction of the two rounds that got you started on this journey.

.38 Special 148 grain WC
Brass Fetcher testing in 10% ordinance gel: @ 650 FPS penetrates 16.0''
Schwartz prediction: 17.93''

000 buck Multi-Ball
Brass Fetcher testing in 10% ordinance gel: @ 790 FPS penetrates 16.2''
Schwartz prediction: 14.16''

Just for grins, let's look at 00 buck:
Brass Fetcher testing in 10% ordinance gel: @ 1340 FPS penetrates 19.6''
Schwartz prediction: 18.92''

All are outside +/- .39 inches and shows why actual testing is needed and not just "paper" predictions as you have no way of knowing if a given round lies within his CI without testing it. Testing is even more critical if your predictions are near the borders of the acceptable range of penetration, especially when it's the low end of acceptability.

BTW, I couldn't help but notice you cherry picked your model here again and presented Machperson's prediction for 000 buck since it was closer to this one actual test.

Back to Schwartz, I also accept him when he says in chapter 6 there is no way to predict the unexpected or adverse effects a barrier may have on terminal performance so testing must be done. He's says the same in his summary recommendations in Chapter 10 - "While there is no substitute for testing ammunition against the actual barriers...". Machpherson has said the same about barriers.

4LD testing probably doesn't matter so much with WCs as it sounds like BG/4LD results are really close with WCs, but AG still does, at least for me and my carry ammo. It's not just because I may have to shot a threat from inside my car (think car jacking, road rage attack, guy attacking half a dozen people in their cars with an ax as happened in my area a few years ago), it's that this test is useful for another reason.

Most importantly, I accept Schwartz when he recommends using a JHP with 16'' penetration, +/- 2''. That's close to DocGKR recommendation of modern barrier blind expanding ammo that penetrates ~15''. See this post:

As noted in the SDPD study and most other OIS incident reviews, bullets in real world shootings tend to have a wider range of penetration than seen in lab studies, for all the obvious reasons previously discussed. In other words, a lot of the time, bullets used in defensive shootings are going to penetrate DEEPER than noted in gel testing (and a lot of time SHALLOWER). In addition, bullets used in the real world tend to act like the 4LD test results.

We have always recommended picking loads that tend to penetrate around 15" or so. The 147 gr HST penetrates about 15.5" in the 4LD test--the test that most closely replicates an unobstructed defensive shooting result. Hmmm, based on that it appears that the HST offers nearly ideal terminal performance for urban and suburban defensive use...

Looking at actual shootings validates (beats?) lab testing and lab testing beats "paper" predictions.

If you're happy with <= 13'' of predicted penetration in BG of non expanding, non barrier blind projectiles, rock on.

To end with a great quote from BehindBlueI's that sums up my thoughts here:

For you? Nothing. I often argue these points not to change the poster's mind. I realize it's tilting at a windmill as the real goal is validation, not learning or a critical examination of the belief. You've been presented with what I would consider compelling counter-arguments while failing to mount an effective defense for your position. I do so for those who might be a blank slate, wander in, and find your fruit salad based testing compelling if it's not countered with facts. If they then also decide fruit salad testing is the way to go, at least they had the opportunity to hear the counterpoint. Carry RIP ammo if you like, absolutely nothing to me until you try and convince others how great it is.

[pettypace]

I accept Schwartz's expedient equation will predict penetration in BG +/- .39 inches with 95% confidence.

Let's look at the actual testing & prediction of the two rounds that got you started on this journey.

.38 Special 148 grain WC
Brass Fetcher testing in 10% ordinance gel: @ 650 FPS penetrates 16.0''
Schwartz prediction: 17.93''

000 buck Multi-Ball
Brass Fetcher testing in 10% ordinance gel: @ 790 FPS penetrates 16.2''
Schwartz prediction: 14.16''

Just for grins, let's look at 00 buck:
Brass Fetcher testing in 10% ordinance gel: @ 1340 FPS penetrates 19.6''
Schwartz prediction: 18.92''

All are outside +/- .39 inches and shows why actual testing is needed and not just "paper" predictions as you have no way of knowing if a given round lies within his CI without testing it. Testing is even more critical if your predictions are near the borders of the acceptable range of penetration, especially when it's the low end of acceptability.

BTW, I couldn't help but notice you cherry picked your model here again and presented Machperson's prediction for 000 buck since it was closer to this one actual test.

Back to Schwartz, I also accept him when he says in chapter 6 there is no way to predict the unexpected or adverse effects a barrier may have on terminal performance so testing must be done. He's says the same in his summary recommendations in Chapter 10 - "While there is no substitute for testing ammunition against the actual barriers...". Machpherson has said the same about barriers.

4LD testing probably doesn't matter so much with WCs as it sounds like BG/4LD results are really close with WCs, but AG still does, at least for me and my carry ammo. It's not just because I may have to shot a threat from inside my car (think car jacking, road rage attack, guy attacking half a dozen people in their cars with an ax as happened in my area a few years ago), it's that this test is useful for another reason.

Most importantly, I accept Schwartz when he recommends using a JHP with 16'' penetration, +/- 2''. That's close to DocGKR recommendation of modern barrier blind expanding ammo that penetrates ~15''. See this post:



Looking at actual shootings validates (beats?) lab testing and lab testing beats "paper" predictions.

If you're happy with <= 13'' of predicted penetration in BG of non expanding, non barrier blind projectiles, rock on.

To end with a great quote from BehindBlueI's that sums up my thoughts here:

================================================== =============================================
There's a lot to chew on here -- some of it a bit tough. So, I'll just take a little bite at a time:

I accept Schwartz's expedient equation will predict penetration in BG +/- .39 inches with 95% confidence.

Let's look at the actual testing & prediction of the two rounds that got you started on this journey.

.38 Special 148 grain WC
Brass Fetcher testing in 10% ordinance gel: @ 650 FPS penetrates 16.0''
Schwartz prediction: 17.93''

000 buck Multi-Ball
Brass Fetcher testing in 10% ordinance gel: @ 790 FPS penetrates 16.2''
Schwartz prediction: 14.16''

Just for grins, let's look at 00 buck:
Brass Fetcher testing in 10% ordinance gel: @ 1340 FPS penetrates 19.6''
Schwartz prediction: 18.92''

All are outside +/- .39 inches and shows why actual testing is needed and not just "paper" predictions

You claim to "accept Schwartz's expedient equation will predict penetration in BG +/- .39 inches with 95% confidence" and then, curiously, you give three examples that you think contradict that claim. But do they? Let's look at those three examples a little more carefully:

In the first example, you say the "expedient equation" (let's call it mTHOR as Schwartz seems to prefer) predicts 17.93" of penetration while Brassfetcher reports 16.0" from actual gel testing. Yet, when I plug Brassfetcher's data into the mTHOR equation I don't get the 17.93" that you claim, but only 14.86". Here's the calculation string I used:

650^0.685*147/7000/(0.39/2)^2/3.14

So, how did you get 17.93"? I'll extend more courtesy then you have shown me and resist the urge to suggest that you might have "cherry picked" the bullet diameter to make your point. I'll give you the benefit of the doubt and accept that you probably just plugged 0.36" into the equation instead of the 0.39" that Brassfetcher recorded.

Of course, it still looks the mTHOR equation is off by more than the " +/- .39 inches." But think about it. Target wadcutters are usually pretty soft -- soft enough so that here they expanded from a nominal 0.36" to a measured 0.39". But if a wadcutter expands, even just that much, is it still a wadcutter. Or more to the point, is it still a sharp edged cylinder? No. That leading edge of the bullet has been rounded over a little. That means it's no longer valid to use a wadcutter exponent on the velocity. We don't know exactly what exponent to use because the deformed wadcutter doesn't match any bullet shape for which we've been given an empirically determined exponent value. But we at least expect any other shape to result in more penetration as shown in the test.

The second example may be more interesting. This is the old Remington Multi-Ball load -- two 000 round balls at 790 ft/s. You claim the mTHOR equation predicts 14.16" . I used this calculation string (790^0.745*69/7000/(0.37/2)^2/3.14) and only got about 13.2". Maybe you used the wrong diameter again. But either way, the duplex load clearly out-penetrated the mTHOR prediction.

You claim that's another example of the model failing to match up with the testing. Maybe you're right. But, in my own testing (albeit in Clear Ballistic gel) I consistently saw duplex loads out-penetrating the mTHOR predictions. And instead of simply assuming the model had failed, I wondered if I was seeing some sort of "drafting" effect wherein the two projectiles gained penetration distance by virtue of sharing the same temporary cavity.

Finally, in the 000 buckshot example you claim the mTHOR equation predicts 18.92". I get about 19.28" using the following calculation string (1340^0.745*54/7000/(0.33/2)^2/3.14) . Not much of a difference maybe. But at least the 19.28" is within the +/-0.39". But either way, I wonder just how the mTHOR model should be applied to a blast of 000 buck. How many balls were in the load? Did they all penetrate to exactly the same distance? Were they all separated by sufficient distances in the gel to get valid results? Did any ball follow too closely in path of another? Given those sorts of questions, I figure it's pretty amazing that the mTHOR prediction got as close to Brassfetcher's number as it did.

Please note that in none of this have I suggested that BG testing is unimportant. I wish I had the time, the energy, the budget, and the facilities to do more testing and to do it all with validated 10% ordinance gel. But I don't.

All I'm saying is that your three examples do not provide compelling evidence that the mTHOR model has failed to meet the +/-0.39" claim.



More later...

[spyderco monkey]

I think the Duplex load for J frames has promise.

Whats needed is a different material then lead.

Namely, ZAMAK Zinc alloy. Bullets have been made out of this before, and its only slightly more difficult to cast then lead (it has to be heated to ~750 degrees rather then ~450 for lead.)

http://castboolits.gunloads.com/show...-boolits-today

At 6.6 g/cm3, ZAMAK 3 is 0.58 the density of Lead 11.34 g/cm3.

--> 2x Lead Wad Cutters 200gr = 116gr for 2x ZAMAK wadcutters (58gr each)

----> Less recoil and higher velocity

We don't know how well a 58gr .355 wadcutter would penetrate.

But, Brasffetcher does have 50yd penetration testing for 000 buckshot (60gr / 0.36"):


60gr 000 Buckshot @ 920fps = 16" penetration:


http://www.brassfetcher.com/Shotguns/Shotguns.html

---> If a 60gr x 0.36" ball @ 920fps penetrates 16", we can reasonably assume a 58gr .355 wadcutter will make it 12"+ at the same speed.

Now comes the issue of speed.

.357 Magnum and 9mm standard pressure are both 35,000psi cartridges.

A .357 loaded with 2x wadcutters will likely have similar case capacity to a 9mm...

And a standard pressure 9mm 115gr goes 1018fps from a LCR:
http://mousegunaddict.blogspot.com/2...t-9mm-for.html

So its reasonable that a .357 116gr 2x wadcutter will be able to hit 950-1000fps from a J frame, using a 9x19 equivalent powder charge.

The Zinc Duplex .357 could be a round with 9x19 levels of recoil (between .38 and .357) that produces 2x 0.355" holes 12"+.

[pettypace]

I think the Duplex load for J frames has promise.

Whats needed is a different material then lead.

Namely, ZAMAK Zinc alloy. Bullets have been made out of this before, and its only slightly more difficult to cast then lead (it has to be heated to ~750 degrees rather then ~450 for lead.)

...

I yet haven't read beyond this point. But thanks in advance both for not rejecting the duplex idea out of hand and for introducing something new to the thread.

[spyderco monkey]

I yet haven't read beyond this point. But thanks in advance both for not rejecting the duplex idea out of hand and for introducing something new to the thread.

I'm happy to contribute.

And I'm glad you brought up the Duplex load. As a ballistics nerd, I absolutely love oddball, niche ammo. AP projectiles, duplex, sabots, flechettes - all are fascinating.

Here's some more info that may help on your quest:

Colts Salvo Squeezbore project:
http://gigconceptsinc.com/Colt-SSB.html





DoubleTap's line of 'Equalizer' Duplex loads:
http://www.doubletapammo.net/index.p...y&path=126_131

https://www.shootingillustrated.com/...mmo-equalizer/



And velocity testing of .38 Special Duplex ammo:
https://www.youtube.com/watch?v=TfCiKmYtKg4


The US Army is also pursuing Duplex ammo for their .50 BMG:
https://ndiastorage.blob.core.usgovc...iSmallArms.pdf

[Caballoflaco]

Cartridge firearms have been widely for over 150 years. If multiple lightweight projectiles fired from a pistol were better than what we have now somebody would have already figured it out. In fact colt did the posted salvo experiment almost sixty years ago. (And were getting 6” groups at 15 yards and 42” groups at 50yards) That companies and governments with millions to spend haven’t found it to be effective should be a clue.


(Note: experimenting with multiple projectiles again (new .50bmg experiments) an area weapon is way different than what the handgun is used for.)

[SiriusBlunder]

.38 WC example

You are right. BrassFetcher used a target WC, not hard cast, which I missed so my first example is not applicable. Sorry.

000 buck multi-ball

Maybe you used the wrong diameter again.

You can't use Brassfetcher's recovered diameter/weight from gel shots in the expedient equation. For non expanding projectiles, the expedient equation uses projectile specs and chrono readings, for expanding rounds it uses recovered weights/diameters from water, not gel, and chrono readings. The whole point of the expedient equation is to use water for a testing medium and make predictions of performance in 10% gel.

000 buck is .36 caliber, and .36 caliber 70 grain @ 790 fps is 14.16'' per expedient equation. When you present Machperson's single ball 16'' prediction instead of the expedient's prediction in post #23, it sure looks like cherry picking a model that predicts an amount you want to match testing (an issue I've had to deal with in real life with folks at work), but I'll grant it wasn't intentional and maybe a result of not running the numbers.

Validity with multi-projectiles hitting gel at the same time?

Since this started, I've wondered about the validity of using models developed for a single project for a duplex load. Part of the reason I keep asking about actual testing with a valid tissue simulant instead of "paper" predictions. However, theSchwartz and you seem to think it's OK to apply here so I haven't expressed it until now. You express doubts about it's use on a 00 load with 8/9 projectiles, but have no issues with 2 projectile load? Why does it work with 2 but not 8/9? Maybe your "drafting" is because you're using Clear Gel that overstates penetration compared to 10% gel and your model predicts performance in 10% gel. Or you are using a single projectile model that doesn't apply to multiple projectile loads.

Testing Resources

You say you don't have the resources to do proper testing but you want to trust your life on a home grown duplex load? Again, drive on.

[Baldanders]

Back in my dark ages of ignorance (when I thought Marshall & Sanow had some validity) I was fascinated by "exotic" ammunition. Now I find it interesting, but the only "exotic" I still wonder about actually using from time to time are multi-projectile loads. (Anyone else remember the .357 Quadramaxium?) It seems like it should work somehow, yet it never quite does.

The InRange boys tested out some very old 7.62x51 experimental rounds some time last year. Seems like it wouldn't be a bad load for increasing hits on snap shots within 100-200 yards or so. If we didn't switch to 5.56, it might have made some inroads. I wouldn't be surprised if it finally becomes a load for machine guns some day

Iinteresting thread, but I will be sticking to JHP and FMJ standard rounds for now. (I still love the Quadramaximum idea though--24 projectiles in one cylinder!)