Ballistics by the inch

Now, about those thunderbolts…

Some weeks back I put up a post about my preliminary experiences with a .460 Rowland conversion for my Glock 21 Gen 4. In it I mentioned how much I like the resultant gun, but also how I was having some problems with magazine wear when shooting full-force .460 loads.

Well, after thinking a lot more about it, as well as discussing it with people online and with the other BBTI members when they were here for the recent tests (one of whom has been a Glock armorer for 15+ years) a couple different strategies emerged for me to test. Briefly, those were:

  • See whether putting in a heavier mag spring would help
  • See whether the problem was due to the case length of the .460 Rowland cartridges (they’re 1/16″ longer than .45 ACP).
  • See whether the problem was due to the *power* of the cartridges rather than the length of the cases.

To test the first, it was a simple matter to get a more powerful mag spring and test it in one of the magazines. I picked up a Wolff magazine spring from Midway and did so.

To test whether it was the simple case length of the .460 Rowland cases, I made up some .460 Rowland rounds using .45 ACP reloading standards.

To test whether it was the *power* of the .460 loads but not the case length was another matter. Here’s where we get to the Don’t Try This At Home part of today’s blog post: I made up a number of .45 ACP rounds which were loaded to .460 Rowland specs.

Let me repeat that again: Don’t Try This At Home. These are wildcat rounds, and potentially dangerous. Shooting them in a gun not rated for .460 Rowland stresses could very well result in catastrophic failure of your gun, of the “KABOOM!” variety. 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. I made up just 10 rounds of each of these loadings, and was careful to make sure I shot them all, so that they didn’t accidentally wind up in a .45 not strong enough to take the punishment.

Here are each of the loadings I made up, just for reference, along with their approximate chrono results:

  1. 185gr XTP bullet, .45 ACP case, .460 Rowland power  1480fps
  2. 200gr RNFP bullet, .45 ACP case, .460 Rowland power  1440fps
  3. 230gr RNFP bullet, .45 ACP case, .460 Rowland power  1350fps
  4. 250gr LFN bullet, .45 ACP case, .460 Rowland power  1250fps
  5. 230gr RNFP bullet, .45 ACP case, .45 ACP power  920fps
  6. 230gr RNFP bullet, .460 Rowland case,  .45 ACP power  925fps
  7. 185gr XTP bullet, .460 Rowland case, .460 Rowland power  1490fps
  8. 200gr RNFP bullet, .460 Rowland case, .460 Rowland power  1420fps
  9. 230gr RNFP bullet, .460 Rowland case, .460 Rowland power  1355fps
  10. 250gr LFN bullet, .460 Rowland case, .460 Rowland power  1265fps

No, I’m not going to give the specific powder amounts for any of those. I used Hodgdon Longshot powder, and you can look up the specs if you want to know more.

In addition, I had these factory loads on hand for comparison, along with their approximate chrono results:

11.  185gr DPX .45 ACP +P  1110fps

12.  230gr GDHP .45 ACP 850fps

13.  230gr JHP .45 ACP +P1040fps

14.  230gr JHP .460 Rowland  1380fps

15. 255gr LFN .460 Rowland1260fps

.460 Rowland loads

.460 Rowland loads

OK, a couple of comments before I go further: those are “approximate” chrono readings because I wasn’t being anywhere near as careful as we are when we do formal BBTI testing. To wit: I was just using one chrono; I wasn’t worried about getting the exact same number of readings (so long as I got three or four, I wasn’t too worried about it); and I didn’t do anything to control for consistent lighting or suchlike. But they should all be in the right ballpark.

So, looking over all those, you will see what I see: that there was a remarkable consistency in power levels, whether you’re looking at my reloads or factory loads, and between those rounds which used either .45 ACP cases or .460 Rowland cases. That tells me that following the published data for .460 Rowland reloads, and making some intelligent decisions on how to adapt those to the .45 ACP cases for purposes of this experiment, was by and large successful. Meaning that I can use those loads to fairly evaluate what makes a difference on the basic problem I was investigating: what is causing the magazine damage and how to resolve it.

So, what conclusions did I draw from all this?

First, the more powerful magazine spring seemed to help with consistent loading. I will be swapping out all the Glock 21 mag springs I have. This makes intuitive sense, since the slide is moving faster when shooting the more powerful rounds.

That doing a little customizing on the magazines also seems to help a great deal. Here’s a pic showing an unaltered magazine and one I have taken a Dremel tool to:

Glock 21 magazines

Glock 21 magazines

Note that these are just the magazine ‘boxes’ — the guts (spring, follower, etc) have all been removed for clarity.

With the altered magazine and stronger spring, any problems I had with Failure To Feed was minimized.

And most important, it is the *power* of the round, not the case length, which seems to cause damage to the unaltered magazines. Shooting the .460 Rowland power loads in the .45 ACP cases demonstrated this.  Conversely, shooting the .45 ACP power loads in the .460 Rowland cases didn’t cause any magazine damage at all.

Two additional notes I want to add: the first is that I had pretty consistent problems with the heavy Lead Flat Nose rounds in all configurations. They kept getting jammed up in transitioning from the magazine into the chamber. I’ll probably continue to experiment with this in the future, but I’m not too worried about it, since many guns run into some ammo specific problems.

The second is that once again I was really impressed at just how well this reconfigured Glock 21 did with .45 ACP loads. Seriously, with the .460 Rowland conversion in place, there was very minimal recoil (more than a .22, but not much) and it was VERY easy to control and shoot the gun well. I suspect that going forward the vast majority of the shooting I will do with this will be using standard .45 ACP reloads, saving the much more powerful .460 Rowland rounds for occasional practice. In this sense, I am thinking of the .45/.460 relationship the way I think about .38/.357 — it seems to be a perfectly appropriate analogy.

Now that I have all this sorted, I can go ahead and write up a formal review. But I thought I would share a little of the process of how I got to this point.


Jim Downey

October 15, 2013 - Posted by | .357 Magnum, .38 Special, .45 ACP, .460 Rowland, Anecdotes, Data, Discussion., General Procedures


  1. Great write up. Wonder what the power of the cartridge has to do with it? Possibly the recoil changing the angle of the shell as it is ejected allowing it to hit the top of the mag on the way out of the chamber? Also, makes me wonder of the potential of using 45super brass to hotter loads when using the Roland spring and compensator. Thanks for sharing.

    Sent from mobile device, please excuse grammar and spelling


    Comment by N2ail | October 15, 2013 | Reply

    • That’s my operative theory about what is happening. So if you remove enough of the front lip of the magazine, it no longer has a chance to hit it.

      And while I wouldn’t want to even hint that someone should do something dangerous, I think there are a number of interesting conclusions one can draw from the data posted in this blog … 😉

      Comment by James Downey | October 15, 2013 | Reply

  2. Good to know someone else in Houston is running a G21 460R. My configuration is slightly different as i am running a LW 6.6″ barrel and their comp rather than the Rowland setup.
    I also have a G30 in process of being converted, and a Mech Tech 1911 CCU in 460R (should get it today).

    Exactly what modifications did you do to your G21?
    -Recoil Spring, power & brand
    -Mag spring, power & brand
    -Close up pics of modified magazines

    Comment by Chris | December 13, 2013 | Reply

    • Actually, I’m in mid-MO.

      The specifics of the conversion are in the earlier post linked:

      And if you click on the image of the two magazines, it’ll give you a full-size detailed pic. The altered mag is the one on the left. The only alteration is the removal of material from the front lip, as shown.

      Good luck with your G30 conversion!

      Comment by James Downey | December 13, 2013 | Reply

      • Yes, I looked there after I sent the post, and followed the mag spring link too, thank you!

        I noticed your load developments as well. How much powder were you using for your max 200gr, 230gr, and 250gr loads? I’m using 12.8gr longshot on 230gr JHP, and 13.5gr on 200gr JHP. Just looking for a comparison as I do not have a chronograph… yet!

        Comment by Chris | December 13, 2013

      • Your loads are a little hotter than what I list above. I’m using the same powder, but at 12.5gr, 12.0gr, and 11.0gr, respectively. Clearly I can increase from there (which I knew), though my loads are pretty close to the factory loads. I would recommend getting a chrono first chance – there’s nothing like being able to actually test your gun/loads directly.

        (And we’ve found that most of the chronos are all comparable in terms of accuracy, until you jump up to something like the Oehler.)

        Comment by James Downey | December 13, 2013

      • When you had run those loads in the .45 ACP brass, did you notice any issues?
        I am running .45 ACP brass in all my reloads (no 460 brass at all, as I am only chambered for .45 ACP) without any issues. The brass I am reloading is mostly Federal, but I have 100 Starline casings, and another 100 Starline +p casings. Most of these casings now have 3-5 loadings each, and 900 rounds through the barrel. The LW barrel I have does an extremely good job of supporting the casing!

        Comment by Chris | December 13, 2013

      • I’ll be getting a chrony in the very early New Year!

        Comment by Chris | December 13, 2013

      • I didn’t find any problems at all with the .45 cases, and they’re just my usual mix of different brands. But as you note, I think the real critical factor is the support from the LW barrel. And I only used them like this one time, so I can’t answer for whether they would break down faster with subsequent reloading.

        That said, I’m henceforth just loading .460 cases (Starline) to those power levels, for safety. Were those much more powerful cartridges to find their way into another .45 not set up to handle them, it could be dangerous.

        Comment by James Downey | December 13, 2013

  3. You are absolutley correct about using those 460 spec rounds in an un-modified .45! I’m pretty sure that would be a trip to the hospital, or worse. At this point, I only have one un-modified .45 (an XDs) plus three 460r units, and I load it with my own .45 super loads which I use a 185gr nosler bullet and starline .45 ACP +p brass with. My 460r spec rounds are Hornady JHP and JSP bullets. This way I have a visual indicator on my own ammo.
    All my shooting buddies know not to use my ammo, unless I specifically make it for them!

    As you pointed out previously that your loads are very close to the published factory 460r loads, and that my loads are a little hotter than you had been using… Being new to handloading, I’m wondering just how far I should go with my loads.. Case bulging would be a first indicator that I’ve gone a little too far, I hope…

    Comment by Chris | December 13, 2013 | Reply

    • I’m just a little more … twitchy … about being extra careful with the “.460R spec in .45ACP cases” because my name is on the blog. 😉

      Case bulge is one good indicator. So is raised or punched-through primers. If cases stick or won’t cycle, that’s another thing to watch for. See this blog post about some wildcat cartridges I worked with in trying to resolve a problem with case length in .44mag loads:

      Comment by James Downey | December 13, 2013 | Reply

      • Fair enough! There are some who claim that this cannot be done at all. However, when you really look at the facts, you can see the flaws in their logic. I’m betting a 460R brass casing will develop the same deformations as with a normal 45 ACP casing, given a specific load.
        An easy way to test this is to hand load 2 rounds. One round in a new 460R casing, the other in a new 45 ACP casing. Powder measure, primer, and bullet all have to be equal (and a known safe loading). Fire both from the same barrel. Then, with a micrometer, measure the OD of the casings from base to mouth. This will give you a baseline to see what the strength of the casings are when compared to each other. Unfortunately, I cannot do this as I am not chambered for the 460R brass!

        Comment by Chris | December 13, 2013

      • That 44mag +p+ 340 grain round is impressive at 1400fps!

        Comment by Chris | December 13, 2013

  4. […] did the .22Mag tests. We did the 9mm Glock Tests. I got my .460 Rowland conversion up and running. And I found some really fun .44Mag +P+ loads, then figured out a simple hack so […]

    Pingback by Wait … it’s 2014?? How did THAT happen? « Ballistics by the inch | January 1, 2014 | Reply

  5. […] 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 […]

    Pingback by .460 Rowland case wall thickness. « Ballistics by the inch | March 22, 2014 | Reply

  6. […] based on a variety of sources and my own experience and experiments in creating loads for the .460 Rowland in 2013, since, as noted, there is very little good information readily available for the .45 Super. […]

    Pingback by Boberg XR45-S: experiments in .45 Super loads. « Ballistics by the inch | December 27, 2014 | Reply

  7. […] in propellant levels so that I surpass published performance numbers for .45 ACP +P. Because of my previous tests, BBTI formal testing, and published numbers for .460 Rowland, I have an upper bound for how the […]

    Pingback by Boberg XR45-S: experiments in .45 Super loads – part II. « Ballistics by the inch | January 23, 2015 | Reply

  8. Did you have any issues with bullet deformation? When I fire a round, the next round chambered looks like it smacked into the bottom of the feed ramp and sometimes won’t even chamber due to the deformation. This was with an altered mag, using your pic as a guide. Running standard mags the issue does not occur. Did you have anything like that happen?

    Comment by Zacharius | June 4, 2015 | Reply

    • Hmm – I haven’t had any problems with the .460 Rowland rounds like you describe. But I did also change out the mag springs with Wolff stronger ones, which might make the difference.

      Comment by James Downey | June 4, 2015 | Reply

  9. […] band for these loads was, and how different guns could handle it. Since I had previously worked up loads for .460 Rowland as well as done a lot of .45 ACP reloading over the years, I figured that I could come up with some […]

    Pingback by Does primer size make a difference? « Ballistics by the inch | October 21, 2015 | Reply

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