.455 Webley MKIV Bullet (HBWC) Testing

[Bigslug]

We just finished up the group buy with MP Molds for this lovely reproduction of the British .455 MKIV:



Fresh from Slovenia with HB and solid base pins, a pair of Cramer rods for each pin, and a steel nose punch. I understand Miha usually makes extras. We were doing both .455 and .457 diameters.

And the end product. . .



To those who aren't familiar with the .455 Webley family of cartridges:

MKI was a 265 grain HBRN atop a longer case than shown using black powder

MKII was this shorter case with the same basic bullet slightly re-shaped to improve stability. This fellow here:


MKIII - aka "The Manstopper" was a 218 grain hollow base, hollow point that was only in military service a little over a year around the turn of the 20th Century due to that pesky Hague Convention nonsense that popped up at around the same time. Sadly, one needs swaging equipment to make those.

MKIV is the bullet above under discussion. 220 grains of the regulation 12-1. I cast these of 20-1 and got 228-229 grains. The MKV was the same bullet made of a low-antimony mix. (99-1 says Wiki). These were around from 1900-1914 when supposedly Political Correctness kicked in again and they decided to go back to the MKII.

The MKII stuck around until the FMJ MKVI arrived just before WWII.

Most of what I've gleaned from the libraries of members here is that all the smokeless variants tended to 600 (ish) feet per second.

If you followed our lengthy thread on the later British use of 200 grain bullets in the .38 S&W, there was a lot of discussion on the theory and performance characteristics of both these and the .455. There was much speculation on whether or not they tumbled & I sacrificed a score of stalwart milk jugs to conclude that the probably didn't unless some glancing strike made them.

So. . .another dive into the pond of pre-WWI terminal ballistics. My last batch of MKII bullets were propelled by 3.4gr of Red Dot at the top end of the British military spec of 580 +/- 30fps, so I backed the charge down to 3.2 for these. Have yet to chrono - will report when I do. Targets were a row of gallon pool chlorine jugs - same size and shape but a bit thicker plastic than those for milk at about ten feet. Keeping a trick from my testing of the MKII bullet, I put sheet of typing paper between each of the jugs to provide any evidence of tumbling (they didn't). Here is what I fished out of Jug #4:



Bullet went through in a nice straight line to the back wall of Jug #4, perforated it, dented the front wall of #5 and bounced back into #4. If thinner milk jugs were used, I'm certain this bullet would have been into #5. The nose was slightly compressed and flared out, but really no change to it's profile. Despite the low velocity, there was enough displacement force to split the first jug along one corner.


This is the entry side of the last jug penetrated #4 - nice, round, nose-first entry.

Terminal performance musings: The FBI Jell-O protocols state that 12-18 inches of penetration in gelatin is the desired amount for a duty pistol load. I've noted that duty hollow points that commonly stop after about 11-15 inches in gelatin are usually fished out of the third (sometimes fourth) milk jug in the stack. It's not a perfect comparison by any means, but it's probably fair to say a gallon jug of water has about the same braking power as 6-7 inches of ballistic gelatin. The FBI prioritizes penetration over expansion, but states that so long as the penetration levels are there, expansion to 1.5x original diameter is desirable (you see a lot of .70-.95 caliber mushrooms). Obviously, there's no expansion here with the .455 MKIV, but it starts big to begin with, stays on the line it starts on, and penetrates closer to what is probably equivalent to that 18" top end of the spec than the jacketed expanders. I have to conclude that one could do a lot worse than this bit of Late-Victorian tech.

The range was too crowded today for putting groups on paper, but it's minute of dog-food can at 25 yards when the operator does his job. More formal accuracy testing to be done next week. To Be Continued. . .

[Outpost75]

IIRC Duncan MacPhearson published that water penetration was about 1.6-1.7 times that of calibrated gelatin. Scroll down to read the abstracts of his published work on Bullet Penetration and links.

[Bigslug]

That would appear to be pretty reasonable math based on what I've seen. It seems that you could multiply your jug penetration by 0.6 +/- .05 and hit the gelatin result somewhere in that range. The ointment-diving flies of course being that with jugs, we're stuck working with 8" increments, and we don't have calibrated jug plastic. That said, the jug plastic is probably a fair analog for skin in that bullets that drastically increase their frontal area will have a harder time getting through it, and like bullet stops on exit-side skin, I've had a lot of impact dents at the intersection between the last jug penetrated and the next one in line. I guess my next trick is to repeat this with the same load using supermarket milk jugs so we can "calibrate" those. If we give this load a fifth jug (32") due to thinner plastic and apply the math above, it should be good for about 18-21 inches of gelatin. Pretty close to what the FBI protocols want - delivered about 90 years ahead of their arrival.

This and select passages from Keith's Sixguns seem to indicate that the essentials were figured out a long time ago, and we had to re-learn them in the 1985-'93 period after Roy Weatherby (or someone) infected the public consciousness with the notion of light weight/high speed.

[Outpost75]

Applicable abstracts and links to the references:

The Schwartz model - QUANTITATIVE AMMUNITION SELECTION presents a mathematical model that allows armed professionals and lawfully-armed citizens to evaluate the terminal ballistic performance of self-defense ammunition using water as a valid ballistic test medium. Based upon a modified fluid dynamics equation that correlates highly (r = +0.94) to more than 800 points of manufacturer- and laboratory-test data, the quantitative model allows the use of water as a test medium to generate terminal ballistic test results equivalent to those obtained in calibrated ten percent ordnance gelatin. The quantitative model accurately predicts the permanent wound cavity volume, wound mass, terminal penetration depth, and exit velocity of handgun projectiles as these phenomena would occur in calibrated ten percent ordnance gelatin and soft tissue. The quantitative model is concisely explained using plain language and illustrated with clearly presented computational examples that provide guidance in every aspect of the model's application. http://www.quantitativeammunitionselection.com/

The MacPhearson Model - This book contains a model of the dynamics of bullet penetration. This model is technically sound and of general applicability, and represents a significant technical advance over what has been heretofore available. This penetration model has been derived from general equations of motion, with validation done by, and empirical constants determined from, special tests. This penetration model is directly related to incapacitation from wound trauma (often called stopping power), a subject that has been of great interest for many decades. The term used in the book for this incapacitation is WTI, for Wound Trauma Incapacitation; this term refers to the production of an incapacitating wound by the bullet parameters (velocity, weight, shape, diameter), and does not refer to any model of this effect...

Bullet Penetration Model Summary
Summarizes the results derived and described in detail in Chapters 6 and 8 in graphs that are understandable and useful to a general reader without technical training. These graphs allow the reader to estimate the penetration depth that would be obtained in gelatin testing for most common bullet configurations. JHP bullet penetration depth can be estimated if typical expansion has been determined by firing the bullets into water (expansion in water, gelatin, or tissue is usually similar in well designed JHP bullets for reasons described in Chapters 5 and 7).

Bullet Penetration Home Page http://pw2.netcom.com/~dmacp/index.html

[Bigslug]

12 rounds for group from sandbags today:



Keep in mind that 3-4 inches is about all I'm good for at 25 yards with GOOD sights, these 4-5" samples with fliers are more about the shooter than the gun or the load. 3.2 grains of Red Dot seems to center about 2.5" above point of aim. Have yet to chrono this.

Compared to my 3.4 grains Red Dot load that averaged 612 fps:



Seems like that wants to hit two inches higher with the same hold. Not really a big deal - this was with front sight level with top of rear for both. The V of the rear sight is actually stepped with a shallower angle at the top, so putting the top of the front sight level with the step for the MKII load should just about do it. It's almost like the Brits were thinking about this stuff. . .

[pettypace]

What if we apply the Schwartz "expedient equation" to predict penetration for the big Webley cartridges? Using Hatcher's values for the .455 Webley (TP&R, p381) here's a calculation you can copy and paste into a Google search and make adjustments as necessary:

600**0.72*265/7000/(0.457/2)**2/3.14

This gives the predicted inches of penetration in calibrated 10% ballistic gel. In this case about 23".

The velocity (600) is raised to an exponent that depends on the bullet nose shape (0.72) for round nose. The bullet weight in grains is divided by 7000 grains per pound. Everything after the 7000 is just dividing by the cross-sectional area of the bullet. The .457 is bullet diameter which is divided by 2 to give the radius and then squared. The 3.14 is just pi.

This calculation agrees closely with charts from MacPherson's modeling and both usually agree pretty well with actual gel testing.

Nose shape factors range from 0.685 for a wadcutter to 0.745 for a round ball.

The Schwarz book is readily available and cheap enough. They practically give away the kindle version. MacPherson is out of print and used copies are crazy expensive. But there is a kindle version that's not too much overpriced.