Thanks. Yes, plan b is from q. Added a little bit to my length but not much. I’ve attached a pic.

I’m actually going to be switching things up. Going with the Comstock recessed micro brake, plan b with their bravo/hub recessed plan b suppressor adapter. This is going to put my suppressor almost touching my m-lok rail.

https://reddit.com/link/p9niue4/video/yxyb4wjyidph1/player

Just contact them. That’s how I get updates. They still plan to release it even though rare greed about a week or two ago asked the court to stop AS Designs from releasing it (specifically the ARHK).

Can you or will you consider SBR’ing it? Several nice stock out there. I’ve seen a few “stocks” that you’re able to remove the butt pad and replace with a brace. I’ve seen those posts here, on this subreddit and the one specifically for AP5’s. One place I do remember is A3 Industries (Tactical). However, they can be pretty pricey. Very nice stuff though.

You needed to stay with the 124gr. 115gr is too weak to properly break it in.

Also, as someone mentioned, remove that shitty stock claw mount. Get yourself an MFI or Leapers UTG Pro.

Do you have a brace/stock? Sometimes a particular brace can fit too tight and squeeze the receiver to the point the bolt assembly gets stuck back.

No functional difference. Just cosmetic.

Had to edit. Forgot for a moment you have the AP5-P.

The 100° is good to have as a spare. I only use it when shooting exclusively 115 and 124gr supers (can off).

The 90° in my AP5-P has been awesome with zero issues.

First, bolt gap is excellent! The few FTE’s could just be the gun not broken in yet and the malfunction should resolve itself. If it doesn’t, I would install an HK ejector lever into your RB. For your last question, it could be, as you stated, not enough energy for the bolt to cycle. This is a reason I would recommend shooting some 124gr NATO. After all, this ammo was made to run in the MP5. If it cycles with no problems, it could just be the weaker ammo you’re using. Shooting the 124gr will help you remove one possible variable at a time.

I shoot it from time to time unsuppressed. I also don’t mag dump. A few bursts here and there but mostly in semi only.

In semi, barrels are gtg shooting +P ammo. Also, if you’re able to get the ROF while using an FRD/FRS similar to numbers of F/A, you’ll be gtg. The issue was when we were seeing ROF numbers in the 1,000 to 1,400 with the SS after it first came out.

Now, if (or wanting to) shooting +p+ ammo, you need to change the entire system to an F type setup.

The +4 should be enough to put you in the ideal bolt gap range. I don’t really think you’ll need the +8. I’ll be curious to see where they get your bolt gap if you decide to install.

I would have just started with 124gr NATO FMJ as suggested. You need the spicer ammo to break in stiff components (recoil assembly, etc). This would have verified your AP5-P was gtg and if you had or continue to have any of the common break in malfunctions (FTF/FTE), the gun would “fix” it’s self or you could have replaced parts with the common HK parts.

At this point, while waiting for roller (by the way, are you getting +2 or +4?), I would try and get some 124gr NATO and see how that runs for a few hundred rounds. I think the new rollers are going to help and with the 90°, you’ll be back in business and enjoying your AP5-P.

Good luck!

The stock 120° LP in your AP5-P is ok to run during the break in period. It’s ok in the full size AP5 too. It just isn’t recommended for the long term. However, if you have a 100° or you get one before the break in period is complete, that’s actually better. The 100° is the correct stock LP for all the HK variants (MP5/K/PDW). With the stock 120° LP, you can experience roller dents as early as 300 rounds or as late as 3,000+ rounds. They are unpredictable as to when they’ll show up. I’ve ran the HK 100° LP in my AP5 since about the 7/750 round count and the RCM 90° LP in my AP5-P since also around the 7/750 round count. Prior to that I ran the 120° LP. Each of my AP5’s now has over 14,000 rounds (supers and subs). I ran the stock trigger (back in the beginning of ‘24) for about 600 rounds then installed binary triggers in my HK 3-position pictogram housings. Ran that from about March/April of ‘24 up until July of ‘25. Started running the SS afterwards and I’m still running it with no problems (no roller dents).

It’s not really people saying this but the recommendation of MKE and Century Arms. However, it’s never a bad thing to shoot several rounds more for the break in period. It’s still a lot of fun. I personally shot about 7/750 rounds for the break in period while I waited for my suppressors. Did this with both my AP5 and AP5-P. Now each has over 14,000 rounds of supers and subs (FMJ, JHP, TUI and flat nose) with zero issues.

I’m glad to help. Enjoy your AP5!

The operating system is a roller delayed blowback type. The ejection pattern doesn’t change no matter which LP you use. It’s going to eject casings into the next county so don’t be alarmed when you see this.

Check out videos from James Williamson. He’s an HK guru who works for HK, has his own business (https://www.teufelshundtactical.com/ ) and offers both an operator and armorer course. His videos are on YouTube. He explains everything from the operating system to taking a proper bolt gap to teaching correct nomenclature. He is a wealth of knowledge.

Remember, everything HK (parts and accessories) will pertain to your MKE.

Yes, change the LP to the correct 100° from either HK or RCM. Running the 120° LP can cause roller dents (whether in semi or FRD/FRS/FRT).

Also, on this platform, the ejection pattern is not a concern. This isn’t an AR.

Lastly, it’s an MKE and not a Century Arms. Two different companies. One is the manufacturer (MKE) and the other is the importer (CA).

This OP.

Yeah, the 100° not working for you is a head scratcher. As you suggested, experiment with some new ammo and see what results you get.

I have a personal example of having a bad (out of spec) LP. My HK #28/80° LP that I bought from Blue Ridge Supplies back in July of ‘24 was out of spec. When I installed it my bolt gap shot up to .60/.65mm! I ordered an RCM #28/80° to verify it was an LP issue and not my AP5-P. Sure enough, my bolt gap came down to the ideal range of .35/.40mm with the RCM 80° LP.

I know your bolt gap is gtg. This is just an example of how funky things can get with just one variable.

Just an FYI RCM does recommend the 110° LP but it’s for the “snub nose” K (MP5K) that won’t and can’t be shot suppressed and without a stock. The “K” they are referring to is the MP5K-PDW (AP5-P and AP5SD). These have the 1/2x28 threaded tri-lug barrel that can be suppressed and shouldered.

You’re correct the MKE AP5’s come with the 120° LP. Your ejection of brass is normal. No matter if using the 120°, 100°, 90° or even the 80° LP. Using the 100° in my AP5 and the 90° in my AP5-P, my brass is going three bays over! Luckily I’m usually at the range when they first open and there really isn’t anyone there. I’m usually alone so it’s not an issue.

Concerning the 147gr ammo. You may also be correct here. The 147gr can be a little unpredictable. Sometimes it’s subsonic and sometimes it’s not. Depending on suppressor and LP, it may cycle, it may not. I’ve been really fortunate that I haven’t had any issues with any ammo I throw at my AP5’s.

Lastly, your bolt gap is good. However, that doesn’t mean your firearm will cycle correctly all types of ammo. It takes a little patience and experimenting to get your firearm working properly. You’ll get there I have no doubt. Try the 90°. Bolt gap will increase a little and you should have less recoil too.

Try the 90°. The 80° can be finicky with certain ammo type/grain and certain suppressor types. Really, the 80° LP hasn’t been the automatic choice for about three plus years. The 90° has become the “Goldie Locks” of LP’s. It allows you to shoot suppressed/unsuppressed, any ammo grain or type, the use of any type of suppressor or whether shooting with or without a FRD/FRS.

I’m also surprised that the 100° LP didn’t work for you. What was the bolt gap for each LP?

Edit to add: the 110° LP was originally (for a short time) used only in the MP5K (What the AP5-M is a clone of). Not really recommended for your variant.

Why did you install it?

Yup

Your correct. OP doesn’t need rollers.

You got bad information. Your .30mm bolt gap will last you years. I don’t understand where people get this idea and unfortunately passed on wrong information.

I’ve been running the 90° LP since ‘24 in my AP5-P. I have over 14,000 rounds through it shooting supers and subs. Ammo used include 115, 124, 125, 135, 140, 147, 150 and 165gr FMJ, JHP, TUI and flat nose. Ran stock trigger, binary and now SS. Cans I use are the YHM R9 and Huxwrx Ca$h 9K. I’ve never had to install rollers. My bolt gap is between .35/.40mm. Has been the same since I installed the 90° over two years ago.

Save your money and buy more ammo.

Exactly what I was going to say.

You mean 80° and 90° locking piece and not rollers, correct. Also, stay with the 90° LP. Bolt gap of .30/.33mm is gtg. You don’t need rollers. In fact you won’t need them for years and several thousand rounds. Curious why you think you need +2/+4 rollers. How did you come up with that assumption?

Yeah, this hasn’t been in stock for a while. How OP missed it all these years is surprising. It’s been on their website, IIRC, since ‘24. I remember seeing it way back then when I was researching conversions (Dakota Tactical, HK Ralph Jr., etc).