Ballistics by the inch

.460 Rowland case wall thickness.

A friend dropped me a note, after looking over my previous experiments with putting .460 Rowland load power into .45 ACP cases, and asked a fairly simple question: Do you think that the case walls are actually thicker in the .460 Rowland?

Now, I have read several articles over the years which mentioned that the .460 Rowland cases were “stronger” with others saying that the cases were “thicker”. In fact, in the blog post cited above, I myself said:

Even shooting them in a gun designed to handle .460 Rowland power was risky, since the .45 ACP cases do not have the same strength as the .460 Rowland cases.

But is that actually true?

Good question. My Lyman 49th Edition Reloading Handbook doesn’t give case wall thickness for the .45ACP, and doesn’t list .460 Rowland at all. A quick check online also didn’t turn up any case wall thickness specs for either cartridge. As noted above, there are some gun writers out there who claim that the .460 Rowland case has thicker walls “for strength” but this claim isn’t made on the 460Rowland.com site that I could find.

So, being the data-curious guy that I am, I decided to just take some measurements and see what I found.

The only .460 cases I have are all Starline brass (I ordered 500 from them, and supplemented with other brass from factory Buffalo Bore ammunition – again, all of it marked as Starline), and I went through and checked a bunch with my simple calipers. Now, those calipers aren’t the pincer type, just the standard parallel-jaws type, so I only trust the measurements to about halfway down the case. And they all fell into a range of wall thickness from 0.012″ to 0.014″.

Doing the same measurement with ten different ‘marked’ sets of .45 ACP brass I also have readily to hand, the results were almost identical, with the vast majority of cases being 0.012″ or a thousandth of an inch on either side of that. It didn’t matter whether the cases were nickle-plated or marked “+P”. The ‘marked’ brass was as follows:

  • Cor Bon +P
  • ELD
  • Federal Brass
  • Federal Nickle
  • R-P
  • S&B
  • Speer Brass
  • Speer Nickle
  • Starline
  • Winchester

And when you stop to think about it, there would be no reason or way for the case walls to be significantly thicker in the .460 Rowland cartridge, and still allow you to use standard .45 ACP reloading components and dies. If the case walls were substantially thicker, then you’d have to have slightly smaller bullets, if nothing else, and would probably need a different resizing die and/or neck expanding die.

Also, when I was conducting those experiments last summer, I didn’t note any differences in how the .45 ACP cases looked or functioned (when being reloaded) after being shot with .460 Rowland power loads.

My conclusion? That the .460 Rowland cases are no thicker walled than .45 ACP cases. They may still be “stronger”, if there is some metallurgical difference, but I doubt it. The real difference is in whether or not the chamber of the gun in which the ammo is being used is strong enough to handle the much-greater pressure of the .460 Rowland loads. Because remember, the maximum pressure for standard .45 ACP is just 21,000 PSI, and 23,000 PSI for .45 ACP +P — while the .460 Rowland cartridge reaches pressures of 40,000 PSI.

Of course, there are additional factors to consider (like recoil and timing) with the .460 Rowland cartridge, so you can’t just make the chamber of the gun stronger and then start putting those kinds of loads into .45 ACP cases. And you really wouldn’t want to accidentally put such power into a ‘normal’ .45 ACP gun — that could lead to catastrophic failure of the gun, and result in serious injury or death. So it still makes ALL KINDS OF SENSE to only load the longer .460 Rowland cases with that much power.

 

Jim Downey

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March 22, 2014 Posted by | .45 ACP, .460 Rowland, Anecdotes, Data, Discussion. | , , , , , , , , , , , | 6 Comments