The Ultimate Firearms Destination for the Gun Lifestyle

The Multi Caliber Glock Solution for Ammo Panics: Hail Hydra

Once upon a time, old-school gun writers had customized project guns with individualistic names. Jeff Cooper had “Baby,” a big-bore Brno dangerous game rifle. Elmer Keith’s more prosaically named “No. 5” was an important step in the development of the .44 Magnum cartridge. Jack O’Connor had … well, perhaps he had a name for his favorite custom rifle, but I never read hunting magazines when I was little, so I have no idea what it was.

If more consideration were given, this project gun would’ve had a name from the beginning, but it wasn’t put together specifically to write about but rather to serve as a hedge against future problems.


In light of current events, though, let’s call it the “Hydra.” In the mythology of classical Greece, the Hydra was a multiheaded monster; even if you cut one of its heads off, the others could cause trouble for Hercules and the other Greek heroes. In the reality of 2020 America, this Hydra is a Glock with multiple chamberings — even if you cut one off from its ammunition supply, the others can solve problems for this American shooter.

When the Multi Caliber Glock in question was initially purchased, scarcity of ammunition was the furthest thing from the mind. It was 2015 and shelves were groaning with ammunition that, looking back from the lean times of 2020, was ludicrously inexpensive.



multi caliber glock

Glock 35 Gen4: Approximately $650, if you can find a new one in stock right now.
Old stainless LW 9mm conversion barrel: $120ish
Old stainless LW .357 Sig conversion barrel: Discontinued. I think it was $115 on clearance?
9mm RSA, extractor, trigger housing, spring-loaded bearing: $50
Wood burner kit at Walmart: $15

The Gen4 Glock 35 in 40 Smith & Wesson had been traded in at the neighborhood gun shop, Indy Arms Company, and the previous owner had done some light modifications. It had a neatly executed and functional stippling job that also removed the finger grooves and permanently blended in the small beavertail backstrap.

Particularly intriguing, though, was that the prior owner had also converted the pistol over to 9mm. And by “converted,” we don’t mean just dropping in a 9mm conversion barrel, but also swapping out the extractor, spring-loaded bearing, ejector/trigger housing, and recoil spring assembly for the appropriate 9mm parts.

While a 40 S&W Glock will generally run 9mm perfectly fine with just a barrel swap, it’s preferable to have the full suite of caliber-appropriate parts for best reliability.

Converted to 9x19mm, the Gen4 G35 could now take advantage of all that sweet, cheap 9mm that was so thick on the ground in those days. A few more modifications helped it blend in with the other Glocks in the safe. 


A combination of a fresh minus connector, the green “NY1” trigger return spring, and an SSVi Tyr trigger were installed. This mix results in a trigger weight that’s six and a half pounds according to an RCBS trigger scale, nominally a pound or so heavier than the standard factory Glock trigger — but the weight is even across the entire length of the trigger pull, and the trigger resets with authority.

The OEM Glock extended magazine and slide releases were swapped for more carry-friendly Vickers Tactical equivalents from Tango Down. Additional exterior modifications were limited to a set of Ameriglo I-Dot Pro sights and a Striker Control Device (aka “the Gadget”) from Tau Development Group.

Basically, this was a 9mm backup to a Gen4 Glock 34 MOS for classes, matches, and ammo testing … but that’s not all!

See, while all the 9mm parts had been installed, the original Gen4 40 S&W-specific parts were also included in the case, along with the three factory .40-cal 15-round magazines.

40 S&W + 9mm

During normal times, this would generally rate a shrug and a “So what?” By 2016, the cognoscenti generally considered the 40 S&W round to be pretty passé. Both the private citizen CCW market and the LE world were well underway in swinging back to 9mm as the carry and duty round of choice. 

9mm, 357 sig, .40 caliber

Left to right: 9mm Europellet, 357 Irrelevant, and 10mm Short.

At local shops, the selection of 40 S&W pistols, both new and used, dwindled from almost half the pistol selection to a couple shelves in a small showcase, shared with the revolvers. The big Indy 1500 gun shows were awash in used LE trade-in 40 S&W pistols … quality Sigs, Glocks, and Berettas … for prices as low as $300 or so. Stick a fork in 40, it’s done, right?

Not so fast. It’s not like 40 S&W doesn’t actually work. In fact, with quality loads, the terminal ballistic performance of the round is nearly ideal, especially through the various barriers used in FBI testing — that’s why the round was developed and adopted, after all.

In fact, even Dr. Gary Roberts, noted terminal ballistics SME, said that if he were doing “a lot of LE work around vehicles,” he’d be tempted to carry a pistol in 40 S&W. This isn’t surprising, since the 165- to 180-grain bonded loads are among the best service caliber loads against intermediate barriers like sheet metal and auto glass.

However, the downsides to 40 S&W are threefold:

First, the increased recoil not only drives down qualification scores for minimally trained officers but it’s also harder to shoot fast and accurately for everybody. There’s a reason action pistol games divide scoring between major and minor calibers, after all. “Oh, I can shoot it fast just fine!” you may say, but you could certainly shoot 9mm faster and finer.

Second, the high chamber pressure and heavier bullets are harder on guns. Shoot a bunch of ammunition through a “40,” and you’ll wear it out faster than the equivalent pistol in 9x19mm, especially since most are built off the same frames.

Lastly, in identically sized pistols, you’ll give up magazine capacity versus 9mm. Back in the dark days of the national ban on guns that looked like “assault weapons,” my roommate who was toting a 9mm Beretta 92 used to “borrow” the magazines from my 40 S&W Beretta Border Marshal because what was a 10-round magazine for it that could be stuffed with nearly half again that amount of 9mm cartridges. (As best we could tell, the differences between Beretta 92 and 96 magazines were mostly in the markings and the witness holes. The latter certainly functioned well enough in the former.)

multi caliber glock 35

One handgun, three calibers. You should be able to scrounge up one of them at least …

All of this apologia for the 40 S&W round ignores its most appealing characteristic in 2020, this year of plague and disruption: It’s less popular than 9mm. Whether it’s an online ammunition wholesaler or your neighborhood gun store, stocks of 9x19mm get depleted faster … and prices spike more quickly … than those of 40 S&W.

So when an ammo crunch hits, the factory original 40 S&W bits can be swapped back in, replacing their 9mm substitutes. So, what makes this truly a “Hydra?” Well, that would be the third caliber option …

.357 SIG

Even more moribund than 40 S&W this year is .357 Sig. More relevant to the “Hydra” project is the fact that, generally, converting a pistol from 40 S&W to 357 Sig is simply a matter of a barrel swap. In Gen4 Glocks, 357 Sig guns share extractors, spring-loaded bearings, and recoil spring assemblies. Only the ejectors differ, and even then only slightly.

Further, while Glock never released an official 357 Sig pistol in the longslide “Practical/Tactical” G34/35 configuration, that 5.31-inch barrel length really wakes up the chambering. 125-grain Remington Golden Saber Bonded and Federal HST Tactical loads both averaged over 1,400 fps in the longslide G35 with a stainless Lone Wolf conversion barrel (and those are real velocities measured with a chronograph, not optimistic claims made on the cartridge box flap).

When .357 Sig fell out of popularity with LE in the last decade, I took advantage of overstock pricing at a couple wholesalers and built up stock of both FMJ and 125-grain Gold Dots, as I was going through one of my periodic infatuations with bottleneck pistol rounds and … well, it was cheap. Like the late trainer Todd Louis Green, my head knows that 9x19mm works fine, but my heart wants to believe that the bottleneck rocket from Sig Sauer is the hammer of Thor.

There are some disadvantages to 357 Sig, no doubt. It boasts a muzzle blast that has more in common with the 357 Magnum revolver cartridge it was designed to emulate than the service auto chamberings with which it competes. Reloading the bottleneck case is a pain; I sold my dies in disappointment. In fact, even most factory-remanufactured ammunition is subpar. Finally, it comes with high prices and relative scarcity compared to 9mm or 40 S&W … at least in normal times.

multi caliber glock

However, during panic-stricken 2020, everything is scarce. People buying 9mm are being caught off guard by scarcity and paying 40 to 60 cents a round for ammo — that’s just a Tuesday for a .357 Sig shooter, so this is all familiar ground.

Further, while writing this article, frequent checks of the web crawler are frankly making 357 Sig and 40 S&W look pretty good, price and availability-wise, compared to the traditional 9mm. Even if I didn’t have pretty good stocks of all three chamberings before the recent craze, I’d be able to resupply the two larger calibers fairly easily and keep training and shooting matches.


While “Project Hydra” runs fine with 357 Sig, and the added zip the longer barrel is undeniably cool, if we were starting over with a clean sheet of paper, a Glock 22 would be a better base gun than the G35. 

The duty-size 357 Sig is a more proven configuration, and while the longslide is easily carried concealed IWB, the duty-size gun is more concealable under a jacket or overshirt should one choose to use an OWB holster. You give up a small amount of velocity and “shootability,” especially in the more potent chamberings, for a small gain in comfort and concealability, but you carry a CCW gun a lot more than you shoot it.

On the whole, though, the end result is pleasing. It’s been completely reliable in all three chamberings with quality factory ammo, and the 357 Sig barrel adds an extra bit of versatility to the longslide Glock.

With three different calibers to choose from, ammo panics aren’t a cause for panic anymore. 

GLOCK 35 Gen 4

Weight Unloaded: 28.9 ounces (.357 Sig Barrel, Unloaded)
Weight Loaded: 36.4 ounces (15+1 Rounds .357 Sig, Federal 125-Grain HST Tactical)
Height: 5.5 inches
Length: 8.5 Inches


Enter Your E-Mail to Receieve a Free 50-Target Pack from RECOIL!

NEXT STEP: Download Your Free Target Pack from RECOIL

For years, RECOIL magazine has treated its readers to a full-size (sometimes full color!) shooting target tucked into each big issue. Now we've compiled over 50 of our most popular targets into this one digital PDF download. From handgun drills to AR-15 practice, these 50+ targets have you covered. Print off as many as you like (ammo not included).

Get your pack of 50 Print-at-Home targets when you subscribe to the RECOIL email newsletter. We'll send you weekly updates on guns, gear, industry news, and special offers from leading manufacturers - your guide to the firearms lifestyle.

You want this. Trust Us.

2 responses to “The Multi Caliber Glock Solution for Ammo Panics: Hail Hydra”

  1. Greg says:

    My solution was to obtain several handguns that were virtually identical except for caliber. I have two 3rd gen Smiths, one in 9mm, and one in .40. I also have three and a half last (?) generation Astras. A 9, a .45, a .38 Super, and a barrel/slde setup in .40 (hence the “half”).

  2. Vermonster says:

    Did something basically identical but with a G31 I found for dirt cheap three years ago. Bobbed the grip to take 19 and 23 mags, added .40 and 9mm barrels and parts, and Cerberus is good to go as a foragers pistol. If I ever find a .22LR conversion kit that doesn’t suck, might need to change the name though.

Leave a Reply

Your email address will not be published. Required fields are marked *

View Comments

  • My solution was to obtain several handguns that were virtually identical except for caliber. I have two 3rd gen Smiths, one in 9mm, and one in .40. I also have three and a half last (?) generation Astras. A 9, a .45, a .38 Super, and a barrel/slde setup in .40 (hence the "half").

  • Did something basically identical but with a G31 I found for dirt cheap three years ago. Bobbed the grip to take 19 and 23 mags, added .40 and 9mm barrels and parts, and Cerberus is good to go as a foragers pistol. If I ever find a .22LR conversion kit that doesn't suck, might need to change the name though.

Subscribe to the Free