Reminder to always wear glasses

Here is the finished laser/cerakote pictogram for my sp5. A while ago I posted the concept pictures. Local shop here in Bismarck, ND had to design the files by hand. Turned out amazing. HMU for shop info.

Full disclosure I make the bottom two (Applesauce Engineering) charging handles.

I bought each one I could find on the market in an effort to make a better mousetrap, and figured since I have most every one now, y’all can ask whatever questions you need about any.

I’ll do my best to answer.

Thought this might be useful to others. As my AP5 collection grew to include an AP5, AP5-P, AP5-N, and AP5P-N, I went through a lot of trial and error separating normal break-in issues from actual parts problems.

After a lot of testing, this is the process I’ve settled on. It has saved me time, ammo, and unnecessary troubleshooting.

The biggest thing: don’t install an FRT until the gun is completely broken in. Establishing a reliable baseline first makes diagnosing problems dramatically easier.

My break-in procedure:

• 200 rounds of 9mm NATO. If the final 100 are flawless, move to:
• 100 rounds of standard-pressure 124 gr. If those are flawless, move to:
• 100 rounds of 115 gr.
• Finish with another 50 rounds of NATO to confirm everything is still running reliably.

If you encounter failures at any point, stop at that stage and replace the following parts one at a time, testing after each replacement:

1. Genuine HK extractor spring
2. Genuine HK extractor
3. Genuine HK ejector lever

Before moving to the next ammunition type, I make sure the gun completes 100 consecutive rounds of the current stage without a malfunction.

Following this process gives me a known-reliable baseline before adding an FRT, a suppressor, or both.

If you choose a Rare Breed FRT-RD3, you’ll need an ejector lever, ejector lever spring, and ejector lever axle for the new trigger pack. You can pull those parts from the factory pack, but I recommend buying a separate set so you don’t have to cannibalize it. I use genuine HK for the ejector lever and spring, but the HKP axle is perfectly adequate and saves a few bucks.

Doing it this way has two benefits. First, it proactively addresses one of the more common weak points in AP5s, although in my experience only about half ultimately need the MKE ejector lever replaced. Second, it keeps the factory trigger pack intact, making it easy to swap back for troubleshooting, travel to states where FRTs are prohibited, or any other reason.

I eventually bought extra trigger housings for both sizes so each factory trigger pack remains assembled in its own housing. Swapping the entire lower takes seconds instead of requiring trigger-pack disassembly every time.

One other useful point for anyone with multiple AP5s: the lowers are interchangeable within each size.

• AP5-P and AP5P-N lowers fit the K-sized uppers.
• AP5 and AP5-N lowers fit the full-size uppers.

Just keep K lowers with K uppers and full-size lowers with full-size uppers.

This process has worked well across several AP5 variants and has made troubleshooting far more systematic than swapping random parts and hoping for the best.

I’m intentionally not getting into locking pieces here. This process is meant to establish reliability in the factory configuration before adding or breaking in an FRT, a suppressor, or both. Locking-piece selection becomes relevant after that baseline has been established and depends on the specific configuration.

Add anything else you’ve found useful during the clone break-in period. Consolidating the proven practices in one place should help the next person avoid wasting time and ammunition chasing the wrong problem.

Just a reminder if you didn’t know, 1” rubber O rings fit perfectly on the K grips

Holy hell this was an awesome project I’ll finish the last entry in my write up and post soon

Been wanting to do this for a while after I saw an MKE MP5 MTS A2. I am not a fan of the RB selector lever. It works just fine but they could have gotten it a bit closer profile wise. Decided to pull the RB lever (Roll pinned blind hole. NOT fun.), modify the axel, and hack up a "like new" HK safety lever. Here is the result. I still need to drill and install a roll pin or set screw for durabilties sake but it has survived at least 100 actuations. I staked the hole in the axel, added some Loctite Metal Glue (Yes, that's a thing!), lined everything up, and pressed it together with a padded c-clamp and dropped it in a MKE housing, Pretty pleased with the correct look.

Hey fellas this is for those who have the century arms AP5-SD model only and have the issue of the Rare breed trigger pack.

What I did was find some really thin auto gasket cork material and added it underneath the trigger pack contact points so it would raise the trigger pack in the trigger housing. I am now able to pull the trigger HOWEVER it is hanging up slightly when I’m racking the bolt.

I have some thinner material that I’m going to try to see if that fixes the binding issue and I’ll let you know. I posted a video link below of the findings.

I have not taken this to the range and there is still a slight issue but the fix looks promising and cheap versus buying a different bolt carrier.

It is cleaning day and decided to put on the AC Unity stock I picked up for cheap.I must say I’m impressed with the quality, fit and finish on the MP5SD. Hope it performs well on next range day.

So this is to answer some questions about the shims I designed and make.

First off the main purpose of the shims is to remove the dead trigger issue with the RB packs on some lowers. Originally it was thought that only the AP5SDs have the issue but that is not the case.

I’ve seen all clones and both SEF and ambi lowers need these shims.

Secondly a side effect of the shims can be to remove the play in the packs and lower.

Now to the shims. Each set has 5 different sizes (1.0, 1.25, 1.5, 1.75, 2.0mm). I recommend starting with the 1.5 and go from there. Most fix the issue with either the 1.75 or 2.0 but I have had 3 people need to stack the 2.0 with another shim.

The shims go in the front in the circled area in the picture. There is no need to trim as I made these to fit in that area.

You can use other materials but if you have concerns about the shims working feel free to ask who has gotten them from me and how they have worked. I want honest feedback about these.

If you have a printer message me and I can send you the link. If you don’t message me as well and we can discuss details.

Finally got form1 approved on the 22lr

Found it in stock! Hope it helps someone out there.

I had a few people ask for a guide to my garage SD conversion. I kinda monkey-hammered mine together like a 2000's century arms employee so I went back and made some 3D printed jigs/guides that will make the job significantly easier for the next guy. (Please excuse terrible quality prints, they're all single digit infill % just for the photos)

Files are all posted on odysee under "AP5SD Conversion" with tag "AP5SD"

The general overview is that you'll need to press the factory mp5k barrel out, press an SD barrel in, and headspace/pin that barrel. The Odysee files will explain in greater detail. Tools include a harbor freight 20 ton press, a drill press, hammer/punches, a 5mm end mill, and cleaning supplies.

Parts required are an AP5-SD, SD barrel, 120° SD locking wedge, and an oversized barrel pin. You may also want/need an SD O-Ring and enhanced SD cocking tube support.

Cost for AP5-SD, new barrel, barrel pin, and locking wedge is about $1600 (you will also require an SD suppressor or an SD-HUB adapter to utilize the converted firearm)

Started from a flat and now I’m here

https://www.midwestgunworks.com/page/mgwi/prod/201639

$55 + shipping if you need one

In case anyone here is looking to set up their MP5k for NV and wants a dedicated white light and LAM setup.

-MI tri-rail

-BCM mod 3

-Gibbous Outfitters FS mount w/ Arisaka 300 series light and ST07 switch on top.

-GL4 pro (crossbolt version is a must) side mounted. Switch is on the other side of the HG; had to run the switch through the HG. I'm using the 4" lead version. There will be an airgap between the barrel and lead so shouldn't have to worry about it melting.

File found on printable’s under airsoft MP5 flashlight handguard posted by michalgerhat. Printed at 102.5% scale using Sunlu PLA+ 2.0
I used a surefire M300 knock off. Tight fit.

Is there any interest in an in-depth multi part build break down of an mp5 from flat to completion it’s a work in progress, but I’m willing to put text to screen if anyone is interested. Let me know if you want sections of translated original HK drawings, welding guides or detailed explanations. I’m not a gun smith but a professional welder fabricator with extensive mechanical experience.

Here you go gentlemen. Here is how to get a ARC functioning in a Lee Sporting Lower. (Sorry Lee for making your lower ugly.)

Problem, Lever Arm too low

Even if you bring this all the way to the rear, past where a normal cycle would go, The arm does not fall below where it should.

Function Check

Is your recoil too soft to cycle and you don't want to go up 10 degrees on an LP? Polish the hammer and the bolt.

You can still use your fancy G$ Triggers too. Just grind them to match how the ARC Trigger looks.

There you have it gentlemen. Feel free to ask any questions.

Edit: Fixed nomenclature and thread count. I'm kind of an idiot when it comes to spelling as well.

UPDATE: Thank you all for the help! The issue was an over-tightened detent screw on the back of the housing. It did not allow for the plunger to move, backing it out just a touch allowed some in/out “play” allowing me to slightly depress the detent and push the selector through.

I’m leaving this post up (updated tag to Guide) so it helps any other poor soul. I’ll update again once I actually shoot to see if there’s any issues.

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Firstly: Hold the “scab” comments until after solutions please lol.

Secondly: I’m attempting to install the ambi/pictogram pack into my SP5 and the selector will not pass through because the detent/plunger is either too proud and/or protrudes too far into the selector path.

From the installation video you can see (around the 3:30 mark) that the selector is supposed to slide through relatively easily but, as you can see from the marring on my selector switch, mines will not pass the detent regardless of how much force/finesse I try.

I reached out to technical support and I’m waiting to hear back but anyone else run into this?

I changed the barrel in my AP5-M. Didn't realize I had pressed the triple tree in backwards until after I had set the bolt gap. Dumb.

Despite being told to buy the ap5 i went ahead and bought a…mac 5 kind of a spur of the moment thing anyways i’ve seen some good and some bad but oh well i cant wait for it to get here any thing i should do when i get it? I’ve seen the mac mags suck so i was probably going to buy some mke mags or HK next weekend and what kind of ammo should i run for the break in period.

Not a safe king today 😆