The second coming of B&T’s GHM9 is more than a firearm. Its Gen2 rebirth comes with a family of accessories that make it the center of a PDW ecosystem. While it may share some features with its U.S. Army-adopted big brother, the APC9, the GHM9 was conceived as a more affordable option aimed squarely at the U.S. market.

We’re aware that affordable is a subjective term, but we’re also aware that Mercedes-Benz and BMW have entry-level models we still can’t afford. The top line here, though, is that the GHM9 gives a lot of what the APC9 offers for a price that’s about 30 percent less. And, in some areas, such as modularity, the GHM9 actually outshines its older sibling.

THE HEART OF THE MATTER

The Swiss gunmaker offers a range of firearms, running from precision rifles to its unique USW pistol. B&T’s first products were suppressors made in 1991. But when the company graduated into full-on firearm development with its release of the MP9 in 2004, the heart of the company, we think, shifted to its PDWs and submachine guns. For example, B&T’s MP9 was an update of the Steyr TMP, and its P26 was an improved version of that hot garbage classic, the Intratec TEC-9. So, B&T’s interest in developing its own subgun platform wasn’t surprising.

OF ARMY CONTRACTS AND RODENTS

According to B&T USA’s CEO Tim Nickler, aside from making guns, cans, and OEMing parts other European defense manufacturers, B&T serviced Heckler & Koch MP5s under contract with various Swiss police units. It was during this time, says Nickler, that company founder Karl Brügger fully realized how laborious and expensive it was to maintain the MP5 and its complex, roller-delayed action. This led B&T to ask why a better, simpler gun hadn’t been manufactured in 50 years. The APC9 was B&T’s answer to that question.

Before the validation of B&T’s APC design came in the form of a $2.5-million U.S. Army contract for the $2,500 PDW in 2018, the company recognized it had an opportunity to expand its line and compete with down-market competitors by releasing a less expensive PDW, with a few of the APC’s key features.

Nickler asked Brügger for a gun to compete with CZ and Sig Sauer’s offerings in the U.S. “He said he’d have it done in 30 days,” recalls Nickler, “‘and you’re going to name it,’ he told me.”

“I felt at the time CZ was our biggest competitor,” Nickler continues, “so what eats scorpions? I looked it up, and lo and behold, there’s Marty Stouffer from Wild America talking about this grasshopper mouse from the Southwest.”

Brügger liked the idea despite Nickler offering it mostly as a joke. The name stuck; the APC9’s little brother was born, and it was christened GHM9, short for grasshopper mouse 9mm.

The GHM line diverges from the APC in its semi-auto only operation, its array of DIY-able barrel, handguard, and stock/brace configurations, its fixed-grip lower receiver, its use of a threaded trunnion instead of the APC’s barrel nut assembly … and of course, its lower price.

GENERATIONS

B&T’s first swing at the GHM9 was a solid hit, but it had room to improve. A couple internal upgrades were in order, as was one big, game-changing boob job that takes the gun to the next level.

First was addressing the Gen1’s failure to feed hollowpoints. It ran FMJs like a runaway RBMK reactor, but B&T initially didn’t set the gun up to run hollowpoints, because it’s a European company and European governments don’t trust their subjects with scary JHP ammo. That mistake is addressed with new feed ramp geometry that’s included in all the Gen2 guns and retrofitted to Gen1 guns by B&T USA upon request.

The new feed ramp improves the GHM9’s appetite for JHPs greatly, but it seems there’s still some rounds it refuses to swallow. Of the four types of hollowpoints we grabbed off the shelf for this review, the GHM9 refused to feed Sig’s V-Crown ammo. Aside from struggling to swallow it, the V-Crown produced unusually crappy groups four times larger than we’d come to expect from that round. We attribute the V-Crown’s accuracy degradation to tip deformation resulting from the bullet slamming into the top of the chamber before barely getting funneled into firing position. For that reason, we dropped the V-Crown from our accuracy test.

The second internal upgrade is a change to the bolt that makes the Gen2 compatible with optional APC9 Pro Glock and Sig lowers. A new bolt profile allows it to strip rounds from both mags.

The last major change from Gen1 to Gen2 is the removable handguard. This is the GHM9’s superpower. The original GHM9’s upper was an uninterrupted, machined extrusion that extended from the buttplate to the front sight. The Gen2 handguard slots onto the upper and attaches with screws top and bottom. The new handguard opens the floodgates for a bunch of barrel and forend options, ranging from the a 4.3-inch barrel and appropriately stubby cover, to the 16.5-inch PCC setup for shooters bent on getting that extra 100-200 fps from their 9-mils.

And that modularity provides the GHM9’s raison d’etre … its pièce de résistance, if we want to get all Euro-like: The ability to use B&T’s newly released GHM9 SD kit.

SCHALLDÄMPFER

The SD kit includes a 4.3-inch base-ported barrel, full-length suppressor, larger diameter handguard, and the barrel removal/installation tool needed to turn the GHM9’s fun dial up to 11. As on the HK MP5-SD, the barrel ports just past the end of the chamber vent gas into the can to reduce the velocity of fired rounds, effectively turning supersonic ammo into quieter, softer-recoiling subsonic rounds.

The barrel is threaded at its base and, somewhat romantically, will only accept mounting by its soul-mated big 10-inch SD kit can — the kit-only handguard has a larger inside diameter than other GHM9 handguards to cover the SD suppressor’s 1.4-inch diameter.

Swapping barrels took 15 minutes and required a heat gun, a vise with leather jaw pads, an adjustable wrench, and the included SD barrel tool. We didn’t even swear. B&T uses medium strength thread locker on the barrel threads, so heating up the trunnion was the most time-intensive part of the operation.

Considering the GHM9 is the Volkswagen to the APC9’s Audi, gewehrvergnügen seems an appropriate way to describe the feeling of shooting the GHM9-SD. Without reserve, we’ll say buying the GHM9 without also placing an order for the SD kit is the only valid use of red-flag laws, in our opinion.

THAT TRUNNION

The GHM9’s trunnion bears some attention. Neither we nor B&T claim it’s never been done before, but it’s a fairly novel arrangement — especially for guys used to wrenching on non-exotics (our polite term for ARs). Its design embodies two opposing ideals: cost savings and overbuilt Swiss engineering. It’s cheaper than using the APC’s two-piece barrel nut arrangement, but it’s also a giant hunk of steel that’s ingeniously immobilized in the upper by bosses machined in the upper extrusion.

This way, the recoil impulse is spread through the whole upper instead of being focused on the eight screws visible on the upper’s exterior. Those just keep the thing from falling out the bottom.

GOING LONG

The GHM9 maximizes its modular moniker with the available 16.5-inch barrel setup. The Swiss don’t seem too taken with the whole free-floated barrel fad and use a barrel bushing at the end of the handguard to minimize barrel whip. The bushing is serious. It has a set screw to clamp the barrel, similar to a set screw-secured gas block. Slapping the 16.5-inch barrel setup on the GHM9 gives it the ability to print 1-inch groups at 75 yards with the right ammo.

IT’S THE HYDRAULICS

The GHM9’s straight, closed-bolt blowback system uses pressure from its dual recoil springs to keep the pistol’s 1.3-pound bolt closed. As with any blowback operated firearm, pressure from the fired round overcomes the combined weight of the bolt and tension of the recoil springs to throw the bolt rearward. This is where the GHM9 shines. While traditional blowback systems dish out a pounding as the bolt slams to a halt at the rear of the receiver, the GHM9 borrows the APC9’s hydraulic buffer, changing the recoil impulse from hardcore to Cinemax.

Sure, there are a bevy of recoil mitigation mechanisms out there, ranging from pliable cushions to Wiley Coyote-inspired spring systems. Each of them requires regular attention as they wear, but the B&T hydraulic buffer is a maintenance-free mechanism that’s practically immortal.

According to B&T’s Nickler, the hydraulic buffer was made to reduce the cyclic rate of the APC9 by 200 to 300 rpm. He says it was just a happy coincidence that it worked so well at mitigating recoil. He was happy to tell us what it does and how well it does it, but beyond saying it’s a hydraulic system, Nickler held back in explaining how it works. He says the buffer was tested successfully with more than 100,000 rounds and was also tested without fluid to simulate a failure. B&T found the tolerances in the part were so tight that the cylinder’s air cushion alone was enough to keep the APC9 spitting bees, even if all the oil were to leak out.

BITS-O-PLASTIC AND THE LAW

The collapsible, or as the B&T calls it, telescopic brace system B&T offers for the GHM9 is a far cry from the slip-on, rubber-and-Velcro jobs we’re used to seeing. The brace is a hearty, metal, rip-it-open, two-position brace that’s easily transformed into a top-shelf, three-position SBR stock using B&T’s $143 screw-on conversion kit. The telescopic brace accessory ships with a couple of spacers screwed to the sliding arms that prevents the use of the last opening position. Use it with a Gear Head Works Tailhook and you’re off to the pistol races with a neutered brace while you wait for your Form 1 to clear.

RELIABILITY

We took the parts from three different GHM9 models and threw them together in one gun to test for tolerance variation between production runs. We separated and disassembled the bolt and lower receiver from one gun, pulled the firing pin and firing pin spring from another, and took the firing pin retaining pin, charging handle, and the hammer assembly from a third, and combined them with the remaining parts into one gun using the SD barrel and suppressor.

This reconstituted GHM9 ran without a hint of trouble, suggesting that B&T’s machine shop holds tolerances tightly from lot to lot.

We also ran the GHM9 with the stock lower and B&T’s house mags, then with an APC Pro lower and Glock mags. Both ran fine with the bolt hold open on last round operating as expected with both lowers. B&T says the APC Pro’s Sig P320 lower works with the GHM9, but it wasn’t available for us to try.

Accuracy with good hollowpoint ammo is impressive in both 6.9-inch Standard and 16.5-inch Sport configurations. Accuracy with Sig’s FMJ’s was less than stellar, though. Looking at the extreme spread and standard deviation values tells us the loose groups had more to do with the ammo than the gun.

The recoil impulse was about the same as a Sig MPX, which is impressive when you remember this thing has a 1.25-pound bolt flying around inside it. Follow-up shots were fast in general, but faster, quieter, and more fun with the SD kit installed. We dig the ergos and handling of the SD setup so much that we doubt this GHM9 will ever see its stock, 6.9-inch barrel mounted again.

LOOSE ROUNDS

We covered a ton of ground in this review, yet we could fill a few more pages with all the other stuff going on in the GHM9. For example, the GHM9 has a novel AR compatible trigger with a hinge that allows activation of the 45-degree safety without resetting the trigger.

Our bottom line on the GHM9 Gen2 is that it’s the basis of an incredibly modular PDW system with the allure of classic Euro engineering. The base pistol, with no brace, is moderately priced for a luxury brand/professional use gun and allows you to start your B&T journey for about $1,500. Then, add on incrementally to make the configuration you want as your budget allows.

We take off points for its inability to run all the hollowpoints out there, but we know there’s no such thing as a free Toblerone. On the upside, though, the GHM9 seems to have a binary attitude when it comes to ammo it doesn’t like. It’ll tell you if it’ll have a problem with a round right away, so working around this weak point is easy.

Like most things based on a subgun design, there’s the roller-delayed party girls on one end of the spectrum and straight blowback last-callers on the other. The holy grail of subgun engineering is designing a low-maintenance action that’ll put rounds where you want without beating you up. B&T nailed it with the GHM9’s dead simple, hydraulically buffered action, wrapping it in an array of modular accessories that make it capable in any PDW or PCC role we can think of.

Find out more from B&T at: bt-arms.com/

[Editor's Note: This article originally appeared in CONCEALMENT #16]

More from B&T USA

• For the first time in 50 years, the Army awarded a new new Submachine Gun contract, choosing the B&T APC9k.
• Not long later, the Miami Beach Police chose the APC9K as well.
• Way back in RECOIL 17, we got our hands on an APC223/556, an APC9/45, and a TP9. Here's the full article.
• In Recoil 45, we took a look at the B&T APC9K and compared it to the old-guard H&K MP5K in this Review.
• To see the the B&T APC9K in action, check it out on this Full Auto Friday on RECOILtv.
• For a more in-depth look at the APC9 Pistol, here's the RECOILtv Gun Room.
• Adaptable and Covert, the B&T Universal Service Weapon turns common pistols into tight-quarters CQB tools.

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