Knights Armament has made a variety of accessories and firearms that have become rather collectible. One of this is a rail system for the MP5. I was just informed that a store called “Presample Depot” has a four in stock at the time of this posting. Figured I would share that with you in case you are looking for one. I have not ever dealt with this company so I don’t know if they are reputable or not. Good luck.
There are several different ways you can purchase the APC9K. The package including the brace, sights, 3 lug adapter, hard case, sling, and cleaning kit is SKU “BT-36045-SB”
It also came with a nice cleaning kit. There is a sling, APC9 PRO manual. It came with the Allen wrenches for the sights and the hand stop/sling loop.
Out of the box, the APC9K has a knurled thread protected installed on the 4.3 inch barrel. The sights and 3-lug were packages in little bags in the case. The handstop/sling loop comes installed on the bottom rail from the factory. This is good as it acts as a nice reference point to help you keep from sliding your support hand forward in front of the barrel. There is not much to hold on too on the front of the gun.
The polymer sights are easily installed by removing the cross bolt with the included Allen wrench. It would be a good idea to use some sort of thread locker if you choose to use the 3 lug mount. A benefit of the 3 lug mount is that it increases the length of the barrel about 1.2 inches which will help prevent you from sliding your hand in front of it.
The push pins on the lower are rather stiff. I’ve had to use a tool to press them. Once the lower is removed, the brace can be pulled out of the receiver. The recoil spring needs to be removed to take the bolt retaining pin out. Then the bolt slides right out of the back of the receiver. This is quick and easy once you have gotten those first 2 push pins out.
The grip has a little storage compartment so you can hide your drugs. It doesn’t appear to be waterproof. You can replace this grip with any standard AR15 grip.
The sides of the receiver have MLOK slots. Magpul 3 slot picatinny rail sections are pre-installed on each side. I thought about removing these, but the gun did seem to get hot after shooting it a bit. These might help keep my hands away from the hot parts. I found the 3-lug adapter kept coming loose while shooting, so thread locker is a must.
A single 30 round magazine comes with the gun. This is the same magazine that the Steyr TMP/B&T MP9/TP9 uses. This clear mag didn’t inspire the most confidence in me, but it ran for flawlessly in this range session. B&T also makes lowers that use other magazines. I want to try the Glock magazine lower.
You can see the rounds stacked somewhat crookedly. While there are only a few rounds in the magazine, the top rounds tilt up, but when a larger number are loaded, the top round tilts down. I wanted to get more photos of that, but my phone was overheating in this cruel December Florida heat.
The magazine can be hard to seat in the gun when fully loaded. I found the left side mag release is hard to use when the magazine is empty and the bolt is closed. The right side works fine all the time.
Ambidextrous non-reciprocating charging handles set on each side of the gun. They often won’t close completely under their own spring power. I wonder if this will get better or worse with use.
I found my self unable to press the right side bolt release down with my firing trigger finger from a firing grip. The magazine release on the right side was easy to use. The left side one had to be depressed quite a bit to work. Not easy to do with left hand trigger finger.
Note that the charging handles lay very close to the side rails. This may make mounting accessories on the side rails difficult. For larger lights or accessories, a person might want to switch to a non-ambi charging handle.
The sights are polymer, and quite frankly don’t feel like Swiss precision. Had you told me that they were Tapco, I might have believed you. I don’t want to say they are bad, but having used them, I wouldn’t say they are good. They might work better on something with a larger sight radius.
There is a little stop on the front center of the front sight that keeps it from flipping up too far. On the rear sight there are two stops. I tried using them as sights and found my impacts very low.
Front sight has a knob for easy adjustment. I had to go 8 clicks up to get a 25y zero. I had lots of glare off the front sight post. It was not good for use in bright sunlight.
Rear sight has a large and small aperture. It can be folded down with either one deployed, but you can not use the knub sights when folded if the small aperture is deployed.
When I was shooting using the small aperture I was getting a good bit of glare and blurriness. I’m not sure if there is a burr in the plastic or if it was the sun reflecting off the shiny plastic.
There is a tiny notch on the top of the large aperture. It is not uniform making it a little harder to use. Once I zeroed the sights with a 25 yard zero, I found up close to the target, using the notch, had me impacting about an inch high from point of aim.
I like the design of the sights, but I feel the polymer post and aperture degrades the usability due to how much glare you can get off the shiny plastic.
Trigger is really nice. Light and short. Little mushy, not perfectly crisp, but probably the best 9mm carbine trigger I have felt out of the box. The safety is ambidextrous and short throw. Large paddles make it easy to flip the safety off, but it is a little harder than an AR to flip the safety on. B&T redesigned the safety to allow you to put this weapon on safe with the hammer down. Because of that, not all aftermarket AR15 trigger will work, but many will.
Some people have complained about the safety, saying it is uncomfortable against the firing finger. I can understand their complain, but I do not have that issue. I would recommend handing this gun before you buy one. Ergonomics feel somewhat inferior to an AR15 lower, but close.
As for the shooting: Very fun. It is handy and pleasant to shoot. The light trigger pull and fast cycling action makes hammered pairs and triple taps extremely easy. The gun doesn’t move very much when shooting it. I found when doing a hammered pair at about 7 yards the second shot would impact directly above the first shot by about 2 inches.
These plastic sights are borderline garbage. The rest of the package is pretty nice.
One last comment. While shooting the AR15 I find it very noticeable when I’ve fired the last shot and the bolt is locked to the rear. On the APC9K I find my self pulling a dead trigger and then realizing I need to reload.
Previously we talked about the rumor of new HK MP5 coming to the market. Link here. Turns out it is true.
You can buy an “HK SP5” pistol that comes with 2 mags and it comes out of the box with all the latest MP5 updates and upgrade. Paddle mag release, 1/2-28 threaded tri-lug barrel, ambi-lower, etc.
MSRP is $2799. Some people are claiming to have purchased them for around $2200.
Downside, it has a Zenith/MKE style block in the receiver to prevent using a full auto bolt.
What does this mean? If you are looking for a Semi-Auto MP5, you can now buy an authentic HK that is ready to go and you won’t have to spend hundreds to change it to what it should have been from the factory. The downside is that these are not likely to be good host guns for auto-sears. It might be possible to mill a full auto carrier to work in these guns, but I don’t know the details.
But I’m not a lawyer, an ATF agent, or an HK expert. Consult with one of them if you plan on using a SP5 as a sear host.
As always, the hardcore nuts are complaining. They say that it has the wrong rear sight and you’d need to swap that out. Some of the people who paid $6000+ for their HK94 are saying that these are a poor finish and bad looking welds and that only a fool would settle for one instead of buying a real authentic vintage HK94. That it should have been threaded 1/2-36. That it doesn’t have a push pin for the front of the lower. That it uses the wrong version of the cocking tube. People will complain about everything given the chance.
If you have been wanting a real HK MP5 and are willing to spend the high dollar for a good semi-auto one. Now is your chance.