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GSG-5 Rimfire Firearms
By Jeff W. Zimba

With the uncertainty of the current political scene and economic times, ammunition of all calibers has been flying off shelves and, when available, it has been higher in price than it has ever been. With the price of military style firearms rising to very high levels and coupled with an even worse availability due to the unprecedented demand, recreational shooters have been waiting for something positive to affect the market. American Tactical Imports (ATI) has stepped forward to address all of these concerns with their GSG (German Sport Guns) line of firearms and their timing couldn’t be better.

Designed as a high-quality rimfire version of the extremely popular H&K MP5 family of firearms, the German-made GSG-5 has hit the ground running and its popularity only seems to be increasing. Since its introduction at SHOT Show 2008, it has developed a huge following and is now offered in several configurations. Other than under close examination, the GSG-5 guns are almost identical in aesthetics to their full-size counterparts and all share the feel and basic function of the originals.

The models available from the manufacturer include the following configurations:

  • GSG-5 Carbine - Resembles the MP5A2 with full-stock and non-functioning suppressor.
  • GSG-5P Pistol - Resembles the MP5A2 with no stock and short barrel.
  • GSG-5PK Pistol - Resembles the SP-89 (or MP5k) with no stock and short barrel.

Several accessories are available directly from the manufacturer and include slings, stocks, mounts, magazines and optics.

Rimfire Rampage

With the GSG-5 guns, chambered in .22 LR, the ammo is far less expensive and much more available than almost all centerfire offerings. Rimfire rifles designed to emulate full-size “tactical” counterparts are not new. The difference with the GSG-5 series of .22 rifles is that it has been designed as a rimfire military-style firearm and not a “sporting rifle” simply wearing new clothes. From the packaging, to the ever-growing list of accessories, the GSG-5 is a quality military-style gun strait from the German factory.

The handling, the weight and the controls of the GSG-5s all painstakingly resemble their centerfire cousins. While the internals are completely different, the fit and function is immediately familiar to the shooter. From the ambidextrous selector/safety to the paddle-and-button magazine release, the feel is close enough to the original to make a low-cost training aid that is already in use in some circles already.

Aftermarket Configurations

Just like the original MP5 family of firearms, it seemed to take about 35-seconds before ingenious entrepreneurs started developing and offering Title-II versions and related accessories to make these new guns even more attractive to the Class III community. The GSG-5 Carbine and GSG-5P soon turned into SBRs (Short Barreled Rifles) with collapsible stocks, resembling an original MP5A3. The GSG-5PK also quickly made the SBR transformation with a folding stock to resemble the MP5K/PDW. Both sport either (or both) 3-lug suppressor adapters or threaded adapters for the popular 1/2x28 accessories on the market. To date this writer has seen no less than 10 different configurations from the 3 basic models.

Range Time

We were able to test several versions of the GSG-5 for Small Arms Review and all ran great and without any hesitation. Several types of ammo were utilized, as you will see in the chart that accompanies this article, and muzzle velocity and accuracy were measured and reported.

The two versions we spent the most time testing were both registered Short Barreled Rifles. They were converted by Kennebec Outfitters of Winslow, Maine, using standard parts available from Gordon Miller of HK Specialists in SC, (

The first gun was an original GSG-5P with a collapsible stock. With a barrel length of 9 inches and an A3-style stock, it strongly resembled a standard “Navy” MP5. The second gun was an original GSG-5PK with a side-folding stock and Gemtech ( 3-lug adapter. The third gun was an original GSG-5PK in the factory pistol configuration and was not used in any major capacity as the function and specifications were identical to the SBR version we were already testing.

Ammo utilized during live fire exercises included 40-grain Federal Champion, 40-grain American Eagle, 40-grain Federal Premium Gold Medal, 40-grain Wolf Match Target and 60-grain Aguila Sniper Subsonic.

All ran without malfunction of any kind until we got heavy in testing with the GSG-PK after firing in excess of 1,000 rounds with no cleaning. At that point, to be certain the malfunctions were only due to the heavy, thick sludge in the well-used gun we swapped to a new GSG-PK and continued firing with no malfunctions whatsoever. All ammo ran excellent, with the faster velocity rounds showing less sensitivity to the dirty gun.

The first tests were to measure muzzle velocity. This was accomplished with a PACT MK IV XP Timer and Chronograph. We used the upgraded infrared screens, placed 8 feet from the muzzle. The SBR GSG-5P was tested first. Having a 9-inch barrel, the fastest average muzzle velocity recorded was with the Federal Champion at 1,173fps. The most consistent ammo was the Aguila Sniper Subsonic with an extreme spread of only 16fps. With the 4.685-inch barreled GSG-5PK the fastest average muzzle velocity measured was with the Federal Champion at 1,081fps. The Federal Champion also proved to be the most consistent ammo with an extreme spread of 42fps. The third round of muzzle velocity testing was a repeat of the previous GSG-PK with the addition of a Coastal Passport silencer. Due to the short barrel leading to the inability to properly stabilize the heavy 60-grain projectile, the Aguila Sniper Subsonic was purposely omitted from this phase of testing so we would not have the potential of a baffle strike. With this firearm/silencer configuration the fastest average muzzle velocity was recorded with the American Eagle ammunition at 1,082fps. The Wolf Match Target provided the most consistency with an extreme spread of 35fps.

Accuracy testing was completed on a portable bench at a distance of 25 yards. All guns were tested using a single shooter and the factory open sights. No optics on any kind were utilized for these tests. Given the probability that the sights were designed more to match the cosmetics of the factory HK sights than to be utilized as a serious target sight, we were somewhat impressed with the groups the guns were capable of recording in the configurations described. Testing for accuracy was only recorded with the unsuppressed firearms.

The GSG-5P had the best 5-shot group when used in conjunction with the Wolf Match Target 40-grain ammo. The best group we recorded measured 1.070 inches. When dropping to the shorter GSG-5PK, the Wolf Match Target also had the distinction of the tightest 5-shot group measuring 1.190 inches. While the guns were fairly consistent with ammo by typically opening up a little as the barrel got shorter there were a few noteworthy abnormalities. First, the Federal Gold Medal actually shot a little tighter with the shorter barrel. The best 5-shot group with the 9-inch barrel was 1.640 inches and the best group 5-shot group recorded with the 4.685-inch barrel was 1.490 inches. This was the only “flip-flop” where a shorter barrel produced a tighter group. The other significant finding was with the 60-grain Aguila Sniper Subsonic ammo. With the 9-inch barreled GSG-5P we recorded an impressive 1.425-inch 5-shot group. Once we started shooting with the 4.685-inch barreled GSG-5PK the 5-shot group enlarged to a massive 5.272 inches and upon inspection it was revealed that some of the projectiles tumbled and impacted the target sideways.


Every model, version and style of the GSG-5, even those heavily modified from the original factory intentions, has functioned at or above the expectations of the author. Given the “more aesthetic than accurate” style of open-sights, the GSG guns proved to be very suitable plinkers and definite training aids to those wishing to shoot on a budget. The appetite for rimfire ammo, ranging in quality and price “from budget to bench-rest” was one of the most amazing attributes of the system. Many experienced shooters who have fine-tuned specific rimfire rifles can attest to the fact that .22 LR ammo has the potential to include manufacturing specifications all over the spectrum, and many guns are finicky of particular ammo brands. The GSG-5 series guns we tested ate everything we stuffed into the magazines and only after an enormous amount of ammo was fired did we experience any type of malfunctions at all. These were immediately rectified with a quick cleaning with no adverse effects. After spending some time with the GSG-5 guns it became obvious why so many people are adding these to their collections as these guns have the look and feel of the HK MP5 family of guns so many of us have come to enjoy. They are cheap to shoot and have an enormous number of accessories making the potential configurations almost unlimited. Even if we looked past the practical applications of training on a smaller ammo or equipment budget, and looked at the fun factor alone, this writer would wholeheartedly recommend the GSG-5 series of firearms to the readers of Small Arms Review magazine.

Registering your own Short Barreled Rifle

Most of the configurations of the GSG-5 we tested in this article are “Short Barreled Rifles” and require prior registration with BATFE. If you would like to own one, there are a few avenues you can use. The first option is to purchase one already registered from a Class III Dealer or Title II Manufacturer. Gordon Miller of sells them all done, and he can be contacted through his website for pricing and to walk you through the purchase process. The other option you have is to register the pistol as a SBR yourself by filling out a BATF Form 1, and upon its return and approval, you can add the stock and other desired accessories.

For those of you not familiar with “making” an NFA firearm, here is a condensed version: The process is almost identical to the paperwork you do when buying any NFA firearm from a dealer. When you buy from a dealer you fill out both sides of a BATF Form 4, mail it in with a check for $200, a few passport pictures, a few fingerprint cards and a Certification of Citizenship form. After the item is approved you can pick it up. The only thing different when you register the item yourself is that you already own it in its Title I configuration, and you send in a BATF Form 1 instead of a BATF Form 4. Once it is approved you can acquire the parts to complete the conversion and assemble it. Do not buy or have in your possession the parts that would constitute the Title II firearm until the application to manufacture (BATF Form 1) has been approved.

To obtain the forms necessary to register your own NFA firearm (individuals may manufacture any NFA firearm or device except machine guns) you can contact your local BATFE branch office or order them on line at: You will need a duplicate copy of a form ATF F 5320.1 (Form 1) - Application to Make and Register a Firearm, A form ATF F 5330.20 - Certification of Citizenship and some BATFE Fingerprint Cards. All are downloadable except the fingerprint cards.

If you have any questions you can find almost every answer at the BATFE website in the Firearms section. The home page is

GSG-5 Specifications (As new, unmodified)

Classification: Pistol
Caliber: .22 Long Rifle
Method of Operation: Semiautomatic, recoil operated
Feed Mechanism: Detachable magazine 10-rds or 22-rds
Barrel length: 9 inches
Rifling: 6-groove, 1 twist in 16 inches
Overall Length: 18.6 inches
Overall Weight: 5.89 pounds
MSRP: $549.99

Classification: Pistol
Caliber: .22 Long Rifle
Method of Operation: Semiautomatic, recoil operated
Feed Mechanism: Detachable magazine 10-rds or 22-rds
Barrel length: 4.685 inches
Rifling: 6-groove, 1 twist in 16 inches
Overall Length: 15.275 inches
Overall Weight: 5.20 pounds
MSRP: $549.99


GSG-5 Rifles and Pistols & Accessories
HK Specialist
146 Ashlan Woods Court
Greer, SC 29651
Ph: (864) 590-8570
Fax: (864) 877-8811

GSG-5 Silencer Adapters
P.O. Box 140618
Boise, ID 83714
Ph: (208) 939-7222
Fax: (208) 939-7804


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