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Ever since I published my first test of Lehigh Defense’s absurdly impressive “Maximum Expansion” ammunition, people have wanted to see it tested in other calibers.  Which I understand, but frankly, I haven’t been in that big of a rush to do so because — well, the .45 Colt version that I tested above is a unique and special situation.  It’s an exceptionally over-long bullet, made possible because of the exceptionally long chambers in the .45/.410 shotshell revolvers.  I didn’t test Maximum Expansion during my .380 Ammo Quest, because the manufacturer’s own specifications showed that it would only penetrate about 7″.  But the 9mm… now that’s a different story . . .

On Lehigh’s site, they claim 12″ of penetration for the 9mm Maximum Expansion round.  Coincidentally, that’s exactly what I’m looking for (a bare minimum of 12″ of penetration through ballistic gel).  Could it be that Lehigh has made a deep-enough-penetrating, gigantic-expanding round that would do for the 9mm pocket pistol, what their mega-expanding round does for the .45 Colt/.410 revolvers?

I tested it, and the results are — not entirely.  It’s a decent performer from a 3″ barrel, but it doesn’t quite hit that 12″ mark; five of the six rounds I tested came in between 11″ and 12″.  The disturbing one was that sixth round; it came in at only 9″.  Now, that’s 9″ through gel, not 9″ through a body; 9″ through gel may or may not be deep enough to reach and disrupt the vital organs.  Generally, I hold pretty firm to the 12″ minimum, so on that basis the Max Expansion won’t be winning the 9mm Ammo Quest, even though the performance was generally pretty decent.

To be fair to Lehigh, their claim of 12″ of penetration is likely based on use from a service- or duty-size pistol, which is pretty much what every ammo manufacturer uses, and I was testing from a 3″-barrel pocket pistol.  Accordingly, I put another three rounds into a gel block, one from the 3″ pistol, one from a 4″ barrel, and one from a 6″ barrel.  The 3″ pistol delivered 11.25″ of penetration, right in line with the prior testing.  The 4″ barrel, however, delivered an outstanding 14.50″ of penetration.  The 6″ pistol’s bullet sheared off at least three of the petals and overpenetrated the block and was lost.

As far as expansion, the bullets do expand to a nice large size; the largest measured a good three quarters of an inch from tip to tip.  However, they’re not really any larger than conventional ammo such as Federal HST; I fired an HST from the same gun and put it side-by-side with the Maximum Expansion, and they’re fundamentally the same basic size.  The Maximum Expansion is a little wider at maximum point, but the cross shape of it means that there are wide areas and  empty areas; the HST is “fuller” and delivers pretty much the same surface area.  This is a significant departure from the .45 Colt version, where the bullet was a gigantic 1.75″ across, and I could actually fit four fully-expanded .45 ACP HSTs within the circle bounded by the Maximum Expansion bullet.  In 9mm, there just isn’t nearly the same amount of metal or the same overall length to work with, so the net result is a bullet that’s about the same expanded size, generally, as conventional premium ammo like the HST.

In the end, I think the Maximum Expansion 9mm did decently well, but wasn’t superior to the conventional ammo in penetration depth or, really, in size.  I think it’s a good performer (although that 9″-depth bullet did concern me).  But I think there are other bullets that perform just as well and some that perform notably better.  When something like the HST will penetrate 15″ from a 3″-barrel gun, it makes me less willing to accept a round that doesn’t quite make it to 12″.  Maximum expansion would be best used from a 4″-barrel gun, where it expands large and penetrates excellently.


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  1. These are among the most useful videos I’ve found yet for concealed carry ammo. Outstanding job presenting this information to us! It’s one thing to hope your ammunition will be effective for CC…it’s quite another to know exactly what ammunition will get the job done.

  2. It’s not entirely surprising. Due to the way this ammo is designed, it clearly works better with longer bullets.

  3. Again, this series is great. Not all manufacturers seem to consider that their SD ammo will be used in 3″ pocket pistols, and the only way to make sure is to test them.

  4. Soooo, I’m guessing the HST’s are the reigning champions of the 9mm ammo quest thus far? It seems every other test has had some form of “compared to the HST” comment in the article.

    • Yup. If you go back and watch the videos, and you should, you’ll find that the HSTs are pretty much the gold standard of the test. Several rounds have done as well, none have really beaten them.

  5. Please,
    Take a look at Robert Eddelman”s VIDEO,,,, Simulated Human torso (Denim/Spare-Ribs(Front&Back)/10″+ClearGel-TEST) Vs Lehigh 9mm Maximun Expantion.. A MUST SEE….. These 4 rounds left MASSIVE 1″ PERMANENT Wound Channels for the first 9″… He ALSO; fired a HST round that Only left a 1/4″ Permanent Wound Channel with equal Penetration…. You would need 4 HST rounds to equal 1 LEHIGH….. I think this Simulated Human Torso is as close to the real thing as you can get…. I take my hat off to Mr. Eddelman (Engineer)….. To me this is a No – Brain-er !!!!!

    Will someone PLEASE,,, explain to me what I failed to understand… Because to Me the Federal HST PERMANENT WOUND CHANNEL looked Beyond PATHETIC in the side by side Clear Gel compared to the LEHIGHs..!!!!!!!! A MASSIVE Permanent Wound Channel is the Dimension to Look At ,,Vs the FBI’s Penetration requirements…Note: The HST Penetration was exactly the Same as the Lehighs…. Best Regards


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