Estimated reading time: 14 minutes
I turned a PTR 9KT into the MP5K I spent years building in video games, then dumped thousands of rounds through it in the real world. The final running total hits $5,008.58, and yes, I would absolutely do it again.
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Table of contents
- My PTR 9KT MP5K Build Started With an Obsession
- MP5 or MP5K? Why I Chose the Compact Route
- PTR 9KT: The American MP5K Clone I Built Around
- MP5K Handguard Setup: More Rail Space Without the Bulk
- Holosun SCRS: The Tiny Red Dot This MP5K Needed
- AB Suppressor F4: Tiny, Titanium, and Perfect for the MP5K
- Turning the PTR 9KT Into an SBR With a B&T Stock
- Fixing the PTR 9KT Trigger, With Another Upgrade in Mind
- Thousands of Rounds Later: This MP5K Is No Safe Queen
My PTR 9KT MP5K Build Started With an Obsession
If you’re a fan of the MP5 platform and its variations, we have this in common. This PTR 9KT MP5K build is my attempt to turn that obsession into the real thing. I am going to detail my own MP5K “build” because I love it so much. I hope that those who want to can use this as a guide to create something truly special for any gun owner. But be warned, this is a costly endeavor.
There are levels to an HK fan. Some build exact replicas from various military operations. Some marvel at the engineering design of various platforms. And some just admire the vibe. I’m probably a combination of the latter two. I’m not from the era that watched British SAS breach the Iranian Embassy while clad in ninja-like attire, brandishing the MP5 platform. In fact, I wasn’t even born yet. However, I grew up on the echoes of the MP5’s legendary legacy. I also find a certain respect for the design of the MP5’s roller-delayed operating system, specifically.
Before I was old enough to purchase a firearm, I was customizing the MP5 to my liking in video games. In fact, I’d bet any FPS video game fan from my generation had a loadout with a red tiger stripe, suppressed MP5 in COD 4. Now that same generation, myself included, is grown up and can spend our grown-up money on real guns. So here’s a rundown of how I recreated an iconic firearm from my virtual childhood in real life, as an adult.
MP5 or MP5K? Why I Chose the Compact Route
There is a myriad of MP5 variants. However, in my head, there are two MP5s: the MP5 and the MP5K. This may be a blasphemous statement to some, but please bear with me for the sake of simplicity.
Both of these have their positives and negatives. MP5 pros include better controllability and increased real estate for attachments. In contrast, the MP5K pros include a higher fire rate in full-auto or forced-reset semi-auto, easily fitting in a briefcase or backpack, lighter weight, and a more compact footprint when deployed in CQB.
Obviously, I think the pros for the MP5K outweigh those of the MP5. Naturally, I went this route when purchasing my platform.
PTR 9KT: The American MP5K Clone I Built Around
Ok… it’s not that simple. I want an MP5K, but how do I get one? Good luck getting one from HK themselves. Or, at least that was how it was at the time I was looking to purchase. HK’s own SP5K-PDW was released in 2020, while there was already a bunch of companies selling MP5K clones.
Many of these clones are very high quality and boast excellent reviews of reliability. And by “many,” I mean that. There are a lot of MP5 clone manufacturers. One such company is PTR. PTR gained my interest by being U.S.-based and by using authentic HK tooling in their manufacturing process.
Naturally, I chose to build my dream gun with the PTR 9KT, built on home turf in South Carolina. From this point forward, I’ll refer to this gun as an MP5K, but please keep in mind that it is an MP5K clone called the PTR 9KT.
This gun has a few specific features that I was looking for. First, it has a threaded, tri-lug barrel for suppressor compatibility. Second, it features a section of Picatinny rail for mounting optics without purchasing some weird adapter or claw mount, as you’d have to with many other MP5K options. And finally, the 9KT comes with a Picatinny adapter for mounting a folding brace until the gun can be SBR’d. Lord knows we are SBR-ing our MP5K in the future.
Build list:
PTR 9KT $1,989.00
Running total:
$1,989.00
MP5K Handguard Setup: More Rail Space Without the Bulk
To deal with the real estate issue for mounting attachments to the handguard, I chose to simply acquire a handguard that has a lot of mounting options. The handguard of choice is the Midwest Industries MP5K M-LOK handguard. This handguard provides two full-length M-LOK slots at the 5,6, and 7 o’clock positions. There is also one M-LOK slot located at the 2,3,9, and 10 o’clock positions. This provides 10 different mounting locations for lights, lasers, pressure switches, foregrips, and more.
Naturally, there is a myriad of options for all of these accessories. I knew I wanted a hand stop, a visible laser, and a light at the minimum. After scouring the web for inspiration, I found it at The Firearm Blog.
I copied Nicholas’ setup, choosing a green Viridian HS1 M-LOK Hand Stop with Integrated Laser Sight. This consolidates the laser and hand stop. I also used a SureFire Mini Scout Light Pro, paired with a Unity Tactical Unity Hot Button M-Lok. I linked these using the UE Scout Light Rear Cap. If I can ever afford night vision responsibly, this setup will change slightly to include an IR light and laser.
Build list:
PTR 9KT $1,989.00
Midwest Industries MP5K M-LOK Handguard: $131.95
Viridian HS1 M-LOK Hand Stop with Integrated Laser Sight: $149.00
Mini Scout Light Pro: $379.00
UE Scout Light Rear Cap: $79.00
Unity Tactical Unity Hot Button M-Lok: $108.00
Running total:
$2,835.95
Holosun SCRS: The Tiny Red Dot This MP5K Needed
Remember, one of the reasons I bought the PTR 9KT is because it had a Picatinny rail for mounting optics. This opens up literally endless options for optics. It makes sense to me to have an enclosed red dot on a riser. This narrows our options down significantly. Next, I want this optic to be relatively small to continue the overall theme of the MP5K build. With this consideration, I chose the Holosun SCRS.
The Holosun SCRS is available with a red or green multi-reticle or 2 MOA reticle option. It’s also solar-charging, has a manual and automatic brightness mode, 20,000 hours runtime, shake-awake, IP67 waterproof rating, and many more features. Basically, this micro red dot sight has everything going for it. Oh, and it comes with a riser and mounts to a Picatinny rail. Perfect.
Build list:
PTR 9KT $1,989.00
Midwest Industries MP5K M-LOK Handguard: $131.95
Viridian HS1 M-LOK Hand Stop with Integrated Laser Sight: $149.00
Mini Scout Light Pro: $379.00
UE Scout Light Rear Cap: $79.00
Unity Tactical Unity Hot Button M-Lok: $108.00
Holosun SCRS: $317.64
Running total:
$3,153.59
AB Suppressor F4: Tiny, Titanium, and Perfect for the MP5K
Because the 9KT has both direct thread and tri-lug mounting options for suppressors, I have nearly endless options available to choose from yet again. To narrow these options down, I had two criteria a suppressor had to meet: lightweight and short. At the time, the best 9mm suppressor that fit these criteria perfectly was the AB Suppressor F4. I would even say that it is still the best, even with sound suppression performance being thrown in as a consideration.
The AB Suppressor F4 is a fully titanium can with a 1/2×28 TPI direct thread mount. It’s also short, coming in at 4.9 inches long. This suppressor adds less than 4.5″ in overall length to my MP5K, suppressing it well. On top of this, it only weighs 4.5 ounces! When I first picked this suppressor up from my FFL, I had to open the box it came in to make sure it was even in there.
Build list:
PTR 9KT $1,989.00
Midwest Industries MP5K M-LOK Handguard: $131.95
Viridian HS1 M-LOK Hand Stop with Integrated Laser Sight: $149.00
Mini Scout Light Pro: $379.00
UE Scout Light Rear Cap: $79.00
Unity Tactical Unity Hot Button M-Lok: $108.00
Holosun SCRS: $317.64
AB Suppressor F4: $580.00 + $200 Tax Stamp
Running total:
$3,933.59
Turning the PTR 9KT Into an SBR With a B&T Stock
How can you own an MP5K and not convert it to an SBR? I couldn’t.
First, I applied for a Form 1 which makes it legal to convert your firearm to an SBR… well, partially. You also have to permanently mark the receiver with the required identifying information, among other things. If you’ve completed the legal jungle gym that is the SBR process, you know it was hard the first time, but easy once you know what to do. For a guideline on this process, check out this detailed how-to by National Gun Trusts.
As soon as the Form 1 was approved, I purchased a buttstock from B&T. I went with their BT-20155 polymer folding stock with adapter for the MP5. Buttstock options for the MP5K are basically split between collapsible and folding options. I like the look of the collapsible buttstock, but prefer the feel of the folding stock. Ultimately, ergonomics won and I chose this buttstock from B&T.
Build list:
PTR 9KT $1,989.00
Midwest Industries MP5K M-LOK Handguard: $131.95
Viridian HS1 M-LOK Hand Stop with Integrated Laser Sight: $149.00
Mini Scout Light Pro: $379.00
UE Scout Light Rear Cap: $79.00
Unity Tactical Unity Hot Button M-Lok: $108.00
Holosun SCRS: $317.64
AB Suppressor F4: $580.00 + $200 Tax Stamp
BT-20155: $325.00 + $200 Tax Stamp
Running total:
$4,458.59
Fixing the PTR 9KT Trigger, With Another Upgrade in Mind
The trigger that comes on the PTR 9KT is pretty abysmal. But it’s designed for a submachine gun, so I guess this is only natural. The last upgrade that I made to complete my MP5K build was swapping this trigger for something better. Currently, this means that I have a Timney HK MP5 Two-Stage Trigger installed. This trigger is crisp and light, allowing me to run it as fast as my trigger finger can move.
Still, this isn’t the final evolution of my MP5K. In the future, I want to supercharge my trigger finger speed with an FRT. There are a bunch of different options available for the MP5K, but they’re all very convoluted. Some approaches involve multiple aftermarket components. I won’t bother to mix and match this and that to find the right combination.
Instead, I will wait for a drop-in FRT trigger. Rare Breed currently offers one, but due to the political bull crap they are involved in, I don’t want to give them any of my hard-earned pennies. Instead, I am waiting for AS Designs to release their ARHK drop-in FRT for HK roller-delayed platforms.
The ARHK is described as a 3-position FRT. With this, my MP5K would have safe, semi- and “FRT” functionalities. AS Designs plans on these being available for purchase early in October of 2026.
Build list:
PTR 9KT $1,989.00
Midwest Industries MP5K M-LOK Handguard: $131.95
Viridian HS1 M-LOK Hand Stop with Integrated Laser Sight: $149.00
Mini Scout Light Pro: $379.00
UE Scout Light Rear Cap: $79.00
Unity Tactical Unity Hot Button M-LOK: $108.00
Holosun SCRS: $317.64
AB Suppressor F4: $580.00 + $200 Tax Stamp
BT-20155: $325.00 + $200 Tax Stamp
AS Designs ARHK: $549.99
Running total:
$5,008.58
Thousands of Rounds Later: This MP5K Is No Safe Queen
Yes, I have spent thousands recreating a childhood fantasy gun. I would also do it all over again. The MP5K legacy is timeless, and I know that this will always remain a favorite firearm of mine because of this.
Besides being a huge vibe, this PTR 9KT MP5K build is incredibly functional. It lives on my nightstand and would be a perfect self-defense weapon against anything that goes bump in the night. Through heavy use, I’ve proven this gun to be reliable and accurate as well as quiet and soft-recoiling.
I’ve shot thousands of rounds through this gun at the range. During this time, I’ve found that most bullet designs work flawlessly. However, the MP5 as a platform in general is known to have issues feeding truncated cone projectiles and some hollow point designs. I’ve noted that my PTR 9KT shares this flaw, failing to feed almost all truncated cone projectiles. However, I’ve found most hollow points to not cause issues.
Also, I’ve even taken this MP5K build into the competition shooting world of USPSA. For those who don’t know, USPSA involves running through a course of fire, shooting all targets as accurately and quickly as possible. During this time in the competitive shooting scene, I’ve learned that the proper reloading procedure for an MP5 is lengthy, cumbersome, and slow. Consequently, there are better platforms for this shooting sport, but I can promise if you show up with an MP5 to shoot regardless, everyone will be talking about you.
PTR 9KT MP5K Build Specs and Cost Snapshot
| Base Platform | PTR 9KT |
|---|---|
| Platform Type | MP5K clone |
| Suppressor Mounting | Threaded, tri-lug barrel |
| Optic Mounting | Picatinny rail |
| Handguard | Midwest Industries MP5K M-LOK Handguard |
| Optic | Holosun SCRS |
| Suppressor | AB Suppressor F4 |
| Suppressor Length | 4.9 inches |
| Suppressor Weight | 4.5 ounces |
| Stock | B&T BT-20155 |
| Current Trigger | Timney HK MP5 Two-Stage Trigger |
| Final Stated Running Total | $5,008.58 |
PTR 9KT MP5K Pros and Cons: Expensive, Addictive, Worth It
- Pros: Compact MP5K footprint, soft-recoiling roller-delayed system, strong suppressor compatibility, built-in Picatinny optic rail, ample accessory space with the Midwest Industries handguard, excellent shootability, and proven reliability through thousands of rounds.
- Cons: The build gets expensive fast, the factory trigger is pretty abysmal, some truncated cone projectiles fail to feed, and MP5 reloads are lengthy and cumbersome compared with better competition platforms.
The $5,008.58 Verdict: I’d Build This MP5K Again
That is the ridiculous beauty of this entire PTR 9KT MP5K build. It started with an iconic gun I knew from video games and the echoes of the MP5’s legendary reputation, then slowly turned into something I actually shoot, suppress, compete with, and keep close at hand.
Could I have spent less? Obviously. A lot less. But the point was never to assemble the cheapest possible roller-delayed 9mm. I wanted my MP5K, with the optic, light, laser, suppressor, stock, trigger, and overall vibe that made me want one in the first place. At a running total of $5,008.58, that childhood fantasy certainly wasn’t cheap. After thousands of rounds, I’d still do it all over again.
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Riley Baxter is a seasoned hunter, outdoorsman, and competitive shooter with deep roots in the backcountry. He has guided professionally for bears, bighorn sheep, and other big game across rugged terrain, bringing firsthand knowledge of what gear actually works in the field. When he’s not chasing game or running drills on the range, Riley is likely in the garage customizing his rifles, pistols, or backcountry kit.
A competitive pistol shooter and lifelong firearms enthusiast, Riley brings both precision and creativity to every piece of equipment he touches. Outside of the gun world, he works as a perfusionist in Montana, a vital role in heart surgery that demands attention to detail, critical thinking, and mental fortitude.
Experience:
– Professional Hunting Guide – Guided for bears, bighorn sheep, and more in some of the West’s toughest country.
– Competitive Shooter – Skilled USPSA pistol shooter with a passion for precision and performance under pressure.
– Custom Builder – Enjoys building and tuning firearms and equipment to meet the exact demands of the hunt or the range.
– Experienced Marksman – Experienced in long-range hunting and precision rifles to meet the demands of the terrain of the West.
– Montana-Based Perfusionist – Medical professional accustomed to making critical decisions in high-stakes environments.