Ultimate Roller Delayed Guide: Everything You Wanted to Know And Were Too Afraid to Ask

The story of the MP5 is a wild tale of globe-trotting Nazi scientists, South American battle rifles, and the rapid rearming of Germany in the face of nuclear annihilation. But despite the complexities of its development and inception, the entire system hinges on an accidental discovery and an elementary ancient object: wheels.

How did the simple wheel lead to the development of the gold standard of submachine guns? Furthermore, what makes the MP5 so damn good, and can it actually compete with modern designs? Rest easy, my philomathic friend, by the end of this article, you’ll know all these things and be able to both annoy your wife and impress your friends with your seemingly endless knowledge of German gats.

DIFFERENCE BETWEEN ROLLER-DELAYED AND ROLLER-LOCKED

The mighty wheel was integral to the design of the most infamous machine gun of the Second World War: the MG-42. But interestingly, this wasn’t a roller-delayed gun, but a roller-locked one. The academic difference between the two stems from the bearing surfaces that the small wheels or rollers on the bolt’s side use to either lock the action or delay its rearward travel.

If this seems like a purely semantic distinction, that’s not totally wrong, but the mechanical differences do translate to practical advantages. On a roller-locked system, the rollers create a true mechanical lock between the bolt and barrel extension. Then, the barrel and bolt carrier move rearward together a short distance to unlock and then cycle the action. In other words, a locked-breech design that uses recoil energy.

On the roller-delayed blowback system, the barrel is fixed, and the rollers essentially gear down the energy of the bolt’s inertial energy, which then allows internal pressures to drop sufficiently before extraction.

ROLLER-DELAYED ORIGINS

We mention this because roller-locked firearms directly lead to the development of roller-delayed ones. Mauser engineers in WWII were looking at ways to improve the G43 rifle when they realized its bolt would occasionally bounce during automatic fire, causing it to unlock the breech before it was fully locked. (Basically, slamming home in battery, but bouncing back just far enough to be just out of battery.)

Mauser-employed physicist Dr. Karl Maier realized that this roller-delayed (instead of locked) system could be employed in new guns without the weight complexity of the roller-locked gas system design. The first design out of Mauser to employ this new method of operation was the StG 45(M) developed by Ludwig Vorgrimler.

The StG 45(M) looks very similar to the famous long-stroke piston-driven Sturmgewehr or StG 44, but features a cylindrical handguard that houses the roller-delayed system. The gun would become the progenitor of the Heckler & Koch G3 family of firearms, but first, it needed to overcome some teething issues halfway around the globe.

Only a handful of these guns were actually built by war’s end, and they needed vastly more prototyping and refining before being ready for combat use. Interestingly, this gun (and all of HK’s military arms) might have died with the Third Reich if not for France.

French troops occupied Mauser-Werke in Oberndorf in April of 1945, and with the assistance of the French military intelligence agency, SDECE (Service de Documentation Extérieure et de Contre-Espionnage (External Documentation and Counter-espionage Service)), poached several engineers in a small-scale version of Operation Paperclip.

Ludwig Vorgrimler, along with the majority of the STG 45(M) team, were relocated to the French state arsenal at Mulhouse to work at the Centre d’Études et d’Armement de Mulhouse (CEAM) to develop the roller-delayed concept further. The result was the CEAM Modèle 1950 carbine chambered in .30 carbine (and later 7.65x35mm).

The French military decided to pass on the new gun, not realizing the potential of an intermediate caliber, select-fire weapon, and in 1950, due to both political and monetary reasons, closed the arsenal. But this was an important step in the development of the system that would one day become the MP5; it proved the validity and viability of the roller-delayed method of operation.

GERMAN-DESIGNED SPANISH CETME GOES BACK TO GERMANY

Around this time, Spain was seeking to modernize its military and small arms industry and had heard of Vorgrimler’s designs. So when Vorgrimler found himself without a job, Spain swooped in two months later and recruited him (along with several of his associates) to head a new program to further develop his roller-delayed guns under the CETME or Centro de Estudios Técnicos de Materiales Especiales program in Madrid.

Along with his colleagues, Vorgrimler developed the CETME Modelo 1958 chambered in 7.92x41mm CETME, though this would later be changed to 7.62x51mm to meet NATO standards, under West German pressure.

The gun was a moderate success, with Spain adopting it in limited numbers, but it wasn’t until West Germany held battle rifle trials in 1959 that the G3 rifle we all know and love would come to life. During these trials, the CETME was pitted against a number of 7.62x51mm self-loading rifles, each given a G-number designation. G1 was the FN FAL, G2 the SIG SG510, G4 was the Armalite AR-10, and the now-famous moniker, G3, was given to the modified CETME model 202. After multiple revisions and modifications, the CETME under the G3 name was adopted by West Germany as its new primary infantry rifle.

THE G3 GOES TO ’NAM!

During early testing of potential replacements for the M14, several designs were pitted against Stoner’s space-age Armalite chambered in .223 Rem. One of these competing guns was based off the West German G3 battle rifle. The Ordnance Department called it the T223, and instead of 7.62x51mm, the new gun was chambered in .223 Rem, but was mechanically very similar.

What’s really interesting is that Harrington and Richardson, a company that built M1 Garands in WWII and Korea, bought the rights to build the guns stateside for potential adoption by the U.S. Army. And while this never panned out, the Navy SEALs loved the guns. In fact, several saw action in Vietnam where its 40-round magazine, superior durability, and reliability made it a better choice for SEAL and SOG-style close, brutal combat with overwhelming firepower. 

This gun was essentially an HK33, but it had a few unique aspects such as a bolt-release inside the trigger guard, along with a last-round-hold-open feature. If you want to see one, there are only two left in the world — one belongs to Reed Knight and the other resides in the Fort Sheridan Museum.

A 9MM G3 FOR COPS AND COUNTER-TERRORISTS

Around the same time as the HK33’s development, H&K was adapting their roller-delayed system to pistol calibers, to produce a new SMG with the same manual of arms as the Bundeswehr’s G3 battle rifle.

Originally called the HK54, which designates it as a select-fire carbine chambered in a pistol cartridge, the gun would be adopted by both the Bundesgrenzschutz West German Border Police and the German Bundeswehr special forces as the MP64, with it being redesignated the MP5 shortly thereafter. It was a resounding success, but the MP5 wouldn’t enter the public zeitgeist until the 1980 Iranian Embassy Siege.  

This was when British SAS operatives utilized MP5s and MP5ks to assault the embassy in Princes Gate, London, while rappelling down the building and breaching windows before neutralizing five terrorists and capturing the sixth.

This incident proved to be the best publicity H&K ever received, because shortly thereafter, multiple American SWAT teams began issuing their officers MP5s. Hollywood, too, was smitten with the new tactical sub-gun, with the MP5 appearing in 28 different American movies and television shows in the 1980s alone.

The prominence of the little German SMG in popular media had a profound effect on gun owners, too. Every kid we knew back in the ’90s knew at least four guns by name: the M16, the AK-47, the M60, and the MP5. No one was immune to the propaganda, and we lusted after one for years. When I was finally an “adult” and could buy my own guns, I was disheartened to find out that semi-auto versions were no longer in production, and pre-ban models were worth the cost of eight WASRs AKs.

GOLDEN AGE OF MP5S

Today, that’s not the case. No fewer than four companies either build or import semi-auto MP5 pistols and carbines at prices that are affordable to most shooters. What previously would have cost $2,000 to $3,000 can now be had for a little over a grand. Sure, these Turkish guns might not be quite as nice as the genuine article, but at a fraction of the cost of the old pre-bans, they will last tens of thousands of rounds with regular cleaning and minor maintenance.

WHAT MAKES THE MP5 SO GOOD?

On paper, a 60-year-old design shouldn’t be able to hold its own against newer designs, but the MP5’s combination of durability, accuracy, and low recoil makes it just as relevant today as ever. 

Take a moment to consider the available pistol caliber carbines on the market today. The overwhelming majority of them share two major characteristics. They’re based on the AR-15, and they function via direct blowback.

The former isn’t a bad thing, since the AR-15 is the single most popular (and prolific) centerfire rifle in the United States today, using the form and ergonomics of them on a PCC makes a ton of sense. A shooter doesn’t have to learn a new manual of arms.

But the latter, in my not-so-humble opinion, is a little lackluster. Direct blowback is a great method of operation for PCCs and SMGs alike, but it suffers from two major drawbacks. The first is weight. Since the action isn’t mechanically locked or delayed, the gun relies on a heavy recoil spring and a heavy bolt (or BCG) to delay the opening of the action until internal pressures drop sufficiently. This translates into a gun that is heavier than it needs to be.

The same heavy bolt also causes the second issue with these guns: recoil. While the recoil of a 9mm blowback AR-15 isn’t what anyone would call substantial, it is stouter than it needs to be. For casual plinking or fun at the range, this isn’t a big deal. But if you’re shooting under the clock, this makes for longer splits and slower recovery from each shot’s recoil impulse.

The MP5’s steel construction makes the gun just as heavy as (if not heavier than) a 9mm AR, but it’s the roller-delayed operation that makes it shine. The MP5’s bolt is lighter, and the recoil impulse less than that of a 9mm AR-15. It doesn’t really become apparent until you’re trying to either perform double taps on a steel target or running one very fast in full-auto (or with an FRT).

Under these circumstances, the ultra-mild recoil impulse of the MP5 makes it feel as smooth as a sewing machine. I can personally keep every round of a select-fire MP5 on a IPSC target at 40 yards, and I’m no John Wick.

Also, the MP5s reliability is incredible. I’ve personally seen a German example ran hard at a police training event where it didn’t struggle at all. This, despite the gun dumping three, 30-round mags at a time throughout the day. All in all, the gun chugged through 7,500 rounds with no firearm-related malfunctions. (One polymer magazine failed, and we had a handful of bad primers.)

This kind of reliability combined with excellent accuracy, and soft recoil is what continues to make the roller-delayed gun so popular to this day. It’s no wonder everyone who can import one is trying to.

But this does have one negative effect — there are dozens of choices for both guns and accessories. But fear not, dear reader, we’ve spent a ludicrous amount of time and money procuring a metric ton of these to help you separate the groupies from the rock stars. Also note, none of these guns were donated. They were bought with hard-earned cash to keep you from wasting yours. So, without further ado, let’s jump into the best roller-delayed guns available today, along with the top upgrades.

BEST ROLLER-DELAYED GUNS OF 2026

Best Budget Battle Rifle Option: Century Arms CA-3

Affordable and roller-delayed seem like a combination only spoken sarcastically, but the new basic-tier G3-style guns imported by Century are a hell of a deal. Built from a combination of Portuguese parts kits and American components by PTR of South Carolina, these guns look like they were just picked up off the battlefield from some war-torn country in Africa.

But looks can be deceiving, and what these guns lack in fancy finish, they make up for in build quality and reliability. If you want a G3 and can spare less than a grand, look no further than the CA-3. Just keep in mind that they lack a recoil lug on the sight base, so you’ll have to buy a CA-3 specific mount like those from MFI.

Best Hipster MP5: POF SMG-5

Did you know Pakistan builds MP5s? Now you do. The Pakistani military bought the equipment, training, and rights to build G3 rifles back in 1965. They never bought those rights for the MP5 and instead modified the G3 design into their own version: the SMG-5. These guns are compatible with 99 percent of HK MP5-pattern parts but utilize a steel lower receiver like a G3 instead of a polymer one. (Although, you can replace it with a polymer one.)

Why would you want one of these? Two reasons: They look cool as hell, and their reverse-stretch gun is the most affordable way to get an MP5-K by a factor of two.

Best Overall MP5 Clone: MKE MP5

It was a toss-up between these and the new MAC guns, but the inclusion of a chrome-lined barrel and better welds pushed the MKE guns over the finish line. These guns are very similar (and 100 percent compatible) with MP5-pattern parts and accessories.

Personally, I have two of these guns each with over 10,000 rounds through them and they still run great. Yes, occasionally a shooter gets a lemon, and Century Arms will replace guns that are faulty. I like buying mine from Atlantic Firearms since they will personally handle any returns or issues a shooter might have normally within 48 hours.

Best MP5 SD Clone: HiTec Arms MP5SD

Unlike the pseudo-SD clones coming out of Turkey, HiTec builds their guns with 100-percent American components (unless you choose to have them modify your Turk gun) and even makes their own SD suppressor.

I paired mine with a McClane Defense FRT, and it has been 100-percent reliable (although a huge PITA to clean). Use 124-grain ammo with this setup to have Hollywood-quiet plinking or the ultimate spooky bugout gun.

Most Fun Gun: MKE AP51

I have shot a ton of short-barreled rifles in my life, but this one is on another level. Based on the FR Ordnance MC51 built for the SAS and SBS, this HK51 clone shoots fireballs like a cracked-out wizard having a Vietnam flashback.

But what would you expect with a .308 SBR sporting an 8.3-inch barrel? Many laud it as just a toy since the round loses so much energy, but keep in mind the muzzle energy of a .308 round from this barrel is still substantially greater than a carbine-length AKM or AR-15 in .300 BLK.

BEST MP5 OPTICS AND MOUNTS

This is going to be somewhat subjective, but I’ve put a ton of rounds through these guns, and I own more optics and mounts than I care to admit. Below are my findings.

Best Mounts: I’m not going to make a list of these, since there are only three companies that make MP5 optic mounts that I would trust with my life — B&T, HK Parts, and MFI. There are others, but these are rock-solid, and virtually idiot-proof. For Turkish guns, take the included mount and either sell it or toss it in a trash can. 

They don’t hold zero, and if you overtorque the mounting screws, they destroy the mount. All three of the aforementioned companies make mounts that have, in my experience, held up to negligent levels of use and abuse. Buy once, cry once.

BEST OPTICS FOR ROLLER-DELAYED GUNS

Now that we have some rock-solid mounts, we need to put an optic on our guns. Since shooter preference and application are big influencing factors here, I’ll list a few options and what they’re best used for.

Best Low-Profile Reflex Sight: Trijicon RMR HD

The RMR single-handedly made the concept of a handgun optic a reality for hundreds of thousands of shooters. It wasn’t the first pistol optic, but it was the first to keep the overall size of the gun as compact as possible while being nearly as durable as iron sights. The latest iteration of the RMR, the RMR HD, keeps the best parts of the original RMR’s design, while improving things like optical clarity, battery accessibility, and distortion.

The RMR HD runs for up to three years on a single CR2032 battery and makes a fantastic addition to smaller roller-delays guns like the MP5K with an elevated mount like the HK Parts Raised Universal Optic Mount.

Best NVG-Friendly Optic: EOTech XPS3

Yes, this a little niche, but once you go NODS, you never go back. The XPS3’s large window and multiple night vision brightness settings combined with its relatively high mounting height make it ideal for use with NVGs like a helmet-mounted PVS-14. As a daytime optic, the oversized reticle makes for lightning-fast target acquisition and shooting.

Best .308 Optic: Elcan SpecterDR 1.5-6x

It’s old, it’s heavy, and it can only show either 1.5x or 6x magnification. But the optical clarity of the Elcan is peerless when it comes to variable zoom optics. I’ve had this one for roughly 10 years, and it has always held zero, and offered me absurd clarity even in low light. The only downside is the cost — roughly twice what a Turkish MP5 clone runs. But if you can afford it, you won’t regret buying one if you need a variable optic built for war, not shooting sports.

Best 5.56mm BDC Optic: Trijicon ACOG 4×32 BAC

Twenty years after Trijicon unveiled its optics to the world, the ACOG is still the gold standard for optic clarity. The BAC models offer a BDC reticle with a chevron for fast target range-finding, which is incredibly useful for engaging targets at unknown distances. Like the Elcan, the ACOG isn’t cheap, but it wasn’t designed to be cheap; it was made to be tough and clear.   

Are there other options available that would serve a shooter well? Certainly. But these are the ones that I have seen take use and abuse and keep running. Plus, why skimp on attachments when you’re already buying a high-end machine? It’s like putting store-brand tires on a race car — you’ll never maximize your performance. 

MAGAZINE GUIDE

The single most important aspect of a modern auto-loading firearm is the magazine. You can have the best of the best for everything else, but if your magazines suck, the gun will quickly turn into an awkward bolt-action weapon whose only value is helping you practice malfunction clearing. So, with that in mind, below are the top picks for MP5 magazines.

Heckler & Koch Steel Magazines

These genuine German-made HK magazines are still the gold standard for a reason: They work. Sure, they aren’t cheap, but if you want to be absolutely sure your gun runs, look no further.

KCI Gen 2 Steel Magazines

Very close in quality and function to original HK mags, these Korean-made magazines are substantially more affordable. They’re available in 10-, 20-, and 30-round capacities and cost roughly half of what German mags demand.

Mora Arms Steel Magazines

These magazines out of Taiwan are very similar in appearance to the Korean KCI mags and are similarly priced. I recently grabbed a few to test out, and thus far (1,000 rounds fired), they have been 100 percent reliable. Unlike the KCI magazines, they’re also available in a 15-round capacity if you want an affordable alternative to one of the most unobtainable mags out there.

Magpul D-50 MP

The engineers at Magpul have done it again, they’ve made an affordable drum that actually works. The D-50 MP is a 50-round polymer drum magazine, which features a ratcheting load-assist arm. These drums are the ideal range toy magazine but also serve well as a home defense magazine or the perfect addition to an FRT or full-auto MP5.