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

Advertisements

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

6 Comments »

  1. I thought I saw somewhere that the case web around the case head was reinforced. After all that is where it would be the least supported by the barrel. I got a storm lake extended and threaded barrel for my G30 and been thinking of loading up some Super for it. With the wolf 21lb spring standard 45acp barely ejects out the gun. I just need to get some new brass to work up some loads.

    Sent from mobile device, please excuse grammar and spelling

    >

    Comment by N2ail | March 23, 2014 | Reply

    • The case web being stronger would make sense, and that’s why I specified the limitations in my calipers: I can’t measure that part of the case for comparisons. I’m going to try and get in touch with the technical folks at Starline and see if they can clarify things — since they’re based just an hour or so from me, I might wind up visiting their facility. If I find out anything more, I will post about it.

      Comment by James Downey | March 24, 2014 | Reply

  2. Let me first state that I an not a metallurgist. However, I work as a metallurgical technician and test mild steel every day. So my experience is with steel not brass. That said, I am very aware of the relationship between hardness and yield strength. A hardness test on one Remington ACP case that has been reloaded several times yielded a result of 47 HRB. A Starline Roland unfired case was 69 HRB. I don’t know how that translates to yield strength in brass, but it is a significant difference. To those who want to run 40 ksi in ACP brass, do it at your own risk.

    Comment by John Connor | January 18, 2015 | Reply

    • Excellent comment, John, and thanks for sharing your expertise!

      This is the conclusion I was coming to as well, as I have done research into the .45 Super and .450 SMC cartridges, and how they differ in relationship to the standard .45 ACP case. They’re niche cartridges, for certain, but seem to be the solution to the problem.

      Thanks again!

      Comment by James Downey | January 18, 2015 | Reply

  3. I know this post is 3+ years old. However, I believe you have too many zeros in your measurements. I believe it should be 12 – 14 thousandths (0.012-0.014). You have all of the way thicknesses in ten-thousandths. Just don’t want someone to get confused.

    Comment by Ashley Michael | December 3, 2016 | Reply

    • Good catch! You’re quite right, of course. I have made the correction.

      Thanks for the heads-up, and for visiting the blog!

      Comment by James Downey | December 3, 2016 | Reply


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: