Sunday, April 25, 2021

9mm Major


Disclosure: This is probably a 40 S&W case. I chose it because the bulge resulted from an incompletely supported chamber. Eye-catching, isn't it.

All progress is due to "crazy" people. There are thousands of reasons why things are exactly the way they are and to try anything different is to be crazy.

"9mm Major" is a wildcat designation for a 9mm handgun cartridge that is loaded so that the power-factor (the muzzle-velocity in fps) TIMES (the weight of the projectile in grains) DIVIDED BY (1000) is reliably above 165.

For example, a 124 grain projectile requires a minimum velocity of 1331 feet-per-second to be 9mm Major vs. the 1100 fps that one might get from SAAMI compliant 9mm Luger loads.

Oh, the other thing is that this cartridge uses common, 9mm Luger "9X19mm brass".

That extra velocity comes at a cost of higher pressure. SAAMI sets the maximum pressure for 9mm Luger at 35,000 pounds-per-square-inch. 9mm Major reloads run a wide range of pressures with 45,000 psi being common and 60,000 psi a real possibility.


Why would anybody torture equipment and brass by running 30% to 70% over SAAMI spec?

Because loading 9mm Luger to those power levels provides a scoring advantage in IPSC and USPSA shooting competitions due to how "hits" are scored.

What can we learn from 9mm Major?

When you are riding the ragged-edge, very tiny details make a huge difference.

Let me paint a word-picture:

The 9mm Luger case is straight-walled and short. One way to increase the volume behind the bullet is to not seat the bullet as deeply when reloading it. A typical 9mm defensive load (like Hornady 124gr XTP) might have an over-all cartridge length of 1.06" so it chambers and fires in any SAAMI complaint chamber. The SAAMI length spec for 9mm Luger is a maximum of 1.169" and it is not uncommon for 9mm Major reloaders to push that to the max allowed by their magazines....often 1.18"

Just as increasing the over-all length of the loaded cartridge lowers pressure, inadvertent shortening (often called "bullet setback") will cause it to spike even beyond the 45-to-60ksi range.

How can bullet setback happen?

Inadequate neck tension is one big cause. The reloading die for 9mm reduces the diameter of the outside of the neck and the inherent assumption is that the wall thickness is consistent. Well, it may be within a specific brand of cases but it is not consistent from brand-to-brand. Some cases have thicker material in the neck (good retention) and others have thinner material (less aggressive retention).

Another consideration is the geometry of the ramp that the projectile hits as it is stripped forward and out of the magazine. The ramp lifts the pointy end up and guides it to the chamber. If the ramp is blunt then it exerts more aftward force on the bullet when it first strikes the ramp and starts to lift it up.

In a similar vein, if the surface of the ramp is rough it increases the friction and all of the forces produced when hitting the ramp increase.

The material characteristics and geometry of the projectile's tip and how they interact with the surface material of the ramp can come into play. Remember that time you went down the slide at the playground and the shorts you were wearing rode up? Yeah, no joy there.

Equipment sets

One thing that I found to be useful when researching 9mm Major is that some equipment sets, specifically barrels, are more accommodating to supporting the demands of reloading to  9mm Major pressures. The ramps are polished. The surfaces are nitrided. The chamber has minimum cut-outs for extractor clearance to better support the brass. Free-bore is generous in length and diameter and the tapering of the rifling is gentle. And so on, and so forth.

If I anticipated that I might someday own a handgun, and if I thought it was prudent to have a back-up barrel in stock for repairs, I would certainly research what the 9mm Major competitors were running and give those exact barrels/part numbers very strong consideration.


  1. All I've ever competed in is good 'ole bullseye pistol matches so I'm not familiar with the pistol competitions you mentioned. If the point is to get velocities of 124 gr. bullets up to approx. 1300 fps, why not just go with a .357 Sig pistol? Brass cost, availability?

  2. I would think that reloading the tapered .357 Sig would be a PITA and brass for 9mm is much cheaper. But I believe the point of the thread is that if you want a very robust spare barrel that should last a lifetime, you should get one that is capable of handling 9mm major even if you don't intend to ever shoot those loads. That said, is KKM aftermarket for Glock any good?

  3. Another 'ole bullseye pistol shooter here. The only adventures I've had with bullet setback is with Berry's plated pistol bullets. Think dead soft lead bullet with a single layer of tin foil. Setback was occurring upon bullet impact with the feed ramp in three different 45 ACP pistols. The only way I could get enough neck tension was to taper crimp the living daylights out of the ammo, to the point where you could see a slight "wasp waist" in the rounds with the naked eye.

  4. IIRC, 38 Super was introduced in the 1930s just for this issue: higher velocity for .3550" projectiles (9MM cases are .754" long, the 38 Super case is .895" - just over 18% longer) which does not mean 38 Super Major does NOT have high pressures - more than one 38 Super Open pistol has committed "sudden self dissassembly."

    USPSA has rules regarding how one achieves Major in 38 Super - IIRC, 150 grains is minimum permissible bullet weight, and 38 Super scores as Major only in the Open category, anyplace else it's still Minor. Which is why we have "9MM Major" more rounds in the magazine than .45ACP but with the same scoring advantage as .45.

    And, I agree - when buying spare parts, 9MM Major stuff for 9s and 450SMC or 45 Super for 45ACP makes good sense just on a reliabilty issue (always test, test and test some more with those spares). Pro Tip: Wolff makes recoil springs, IIRC, up to 26 lbs, for some pistols. I have no clue who might make NIJ IIIA ballistic armor shooting gloves.....

  5. If i were to have a gun someday, a threaded barrel seems to be a good idea for future flexibility.

    I think having a spare gun would be more useful and flexible than sinking gobs of money into very top of the line components for an existing unit.

    1. There's no question a spare gun has more value than "spare parts;" if you have to use your gun in "exigent circumstances" it'll languish in a police evidence locker for months, probably years, and it's condition when returned will be questionable, so a spare bang tool is useful. Extra points if it uses the same ammo, holster, and magazines as the primary and the operator controls are all in the same place.

      But, RE: spare parts, the obvious ones are at the top of the list: springs, pins, (including firing pins) screws (if yours uses them), etc. Spare barrels are nice, too; if you might ever want a suppressor, threaded works for that and poses no impediments to normal use.

      Drill bits in variou sizes can be handy, too; 23/64 happens to be .044" larger (~1.1MM) than 9MM bullets, but 3/8" is more common and works much more betterer. Pro Tip: For unknown reasons, it's sometimes recommended to replace barrel, firing pin and recoil spring together, and polish the bolt face on the slide at the same time. No idea why.

  6. My target shooting consists of cardboard boxes with paste on dots and I load .357 mag and .38 special. I also have a Marlin carbine in that caliber and if you shoot 38 special in the carbine and have bullet setback in the mag it will jam. Solution. Is a Lee carbide crimp die. I know the 9 mm uses a different crimp but a crimp die in that caliber should help!

  7. My target shooting consists of cardboard boxes with paste on dots and I load .357 mag and .38 special. I also have a Marlin carbine in that caliber and if you shoot 38 special in the carbine and have bullet setback in the mag it will jam. Solution. Is a Lee carbide crimp die. I know the 9 mm uses a different crimp but a crimp die in that caliber should help!

  8. I went to the range with my grandson and after shooting the .22 for awhile I gave him my 9mm Kahr to shoot. With commercial reloads in the mag.
    The first trigger pull and the gun somewhat exploded in his hand.
    We found all the pieces and I reassembled it that night.
    The ejector is designed to blow out a small panel in the grip above the hand placement should this happen.
    I can only assume that the powder was overloaded.
    I was (and am) grateful for the design consideration.

  9. When Customs and Border Protection started up, a qualification day would include both .40 caliber pistols and 9mm pistols.

    And it didn't matter how many times the firearms staff would advise caution, sooner or later somebody would stuff a 9mm in a .40 caliber magazine and attempt to fire it.

    That resulted in at least two bulged 9mm cases that look a lot like what your photo shows.

    Not enough gas pressure to drive the slide back and no idea where the round ended up after its trip through the barrel.

  10. If you want a really hot load in a 9mm case, I'd suggest looking at 7.62 Tokarev... and if you want a gun to handle a hot 9mm, then get a 9mm barrel for a Tokarev. I have fired 9mm out of a Tokarev adn it is nothign compared to firing 7.62 Tokarev!


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