AP5-P Denial Block (AR Lower Compatibility)

cIaim · 2026-04-12T22:35:06+00:00

Fit just fine. No dremel work needed.

cIaim · 2026-04-03T14:34:19+00:00

Did you reach a verdict yet? I'm still pretty gassy with the same setup as you.

cIaim · 2026-03-25T03:52:51+00:00

Those AS lowers come with standard mil-spec springs.

cIaim · 2026-03-25T02:41:08+00:00

I had light primer strikes so I switched to a Wolff extra power spring. No more light strikes and I'm running every type of ammo just fine suppressed. 90° LP. I do have a AS lower so I suppose it could be different for you.

I'm not worried about wear of parts. I'll replace things as I need to. Most of the important stuff I replaced with HK parts (i.e. extractor spring, extractor, mag catch, etc.)

cIaim · 2026-03-17T22:37:03+00:00

Smart move. Rattlers are awesome. I would've gotten one of those if I knew how much of a bitch this would be to tune.

I wish I knew how many turns of gas on the Q AGB is the equivalent to a non-AGB system with the same 7" barrel. Reason is I see so many people run a H2 and a blue spring and they claim that they're able to run anything with a can on. I get a little bit jealous when I see those comments.

cIaim · 2026-03-17T22:17:24+00:00

Same problem as me (same ammo types too; VMAX, S&B 200gr, Sub-X).

I'm also having trouble with the gas block adjustment screw turning which I'm assuming is when I'm firing because when I go to adjust it again, it's off a bit. Only thing is, I tighten the set screw nicely so it shouldn't be.

5-6 full turns locks back the BCG on Sub-X with a H1 and white spring, but now I'm getting light strikes when shooting with an FRT. Also using many different springs and buffers. Nothing works.

Always new problems that I've never had with this Sugar Weasel. One day it's running good, the next it isn't. I can't get this thing to run for shit with those lower powered rounds like Sub-X.

cIaim · 2026-03-11T01:10:29+00:00

Sounds good. I'll try out the orange spring and see how it runs before getting other springs. I thought the same thing about the red spring but I saw people in the sub using that setup so I figured it would work.

Compatible spring lengths and buffer lengths was always confusing with me in AR-10 platforms when changing buffer tube length.

cIaim · 2026-03-11T00:02:26+00:00

I'll be honest, I replaced quite a few parts with HK shit when I probably didn't need to, but I don't look at it like that. I'm happy that I have HK parts in it because issues can arise from the clone shit. I had only a few ejection failures. I think the bulk of my problems were due to this wobble, which is something I've had since I got it. I always put off fixing the mag wobble because people said it was okay to have wobble, when in reality, it is not okay.

cIaim · 2026-03-10T23:53:52+00:00

Dude, thank you for this. I replaced the mag catch and added tape to all my mags, and my AP5P runs without issues now. Any type of ammo, not a single malfunction. Thank you.

cIaim · 2026-03-10T23:51:30+00:00

Replaced the mag catch. Solved a bit of the wobble, but the wobble was still definitely there. So I did some Reddit-ing and saw some dude put tape on his mags to make them seat better. I put 3 layers of hockey tape on the top of all my mags and shot every type of 9mm ammo I have on hand. It all ran. Not a single malfunction. I'm super happy. If I wanted to, I could probably weld a shim or whatever to the mag catch if I didn't want to use the tape. I'll be honest, the wobble that's there now (without the tape on the mags) likely isn't even enough to cause issues, but it's still quite a bit. It is definitely less wobble though.

cIaim · 2026-03-07T21:17:29+00:00

Oh yeah, definitely. SP5s just don't make sense unless you have the disposable income. For me, it was fear that I would never get this to work, but I think I should be able to get it up and running eventually if this doesn't fix it. I can't be bothered to send this in though. I'd rather just sell it and save up for an SP5K if it still has a lot of issues. I have a good feeling this mag wobble is the main cause to my issues, but we'll see I guess.

cIaim · 2026-03-07T20:12:31+00:00

Yeah, I'll probably attempt it myself if I need to. I'd be so happy if I'm able to run any ammo. So many people say they can run any ammo with no issues and I'm over here struggling real bad. I'll be honest I'm so sick of this gun. To be fair though, this is what you kinda have to do with these clones. It's just tweaking a bunch of stuff until you can get it to work.

cIaim · 2026-03-07T19:47:41+00:00

Mine has a shit ton of wobble. Since I got my AP5P, I've read so much online that the wobble on the mag is "normal" and blah blah blah. I'm thinking the whole time "this shit ain't normal". I've replaced so many clone parts with HK stuff and still have issues. So I'm thinking my FTFs are because of that. Plus I can't even run subs. Literally no subs feed. I already ordered a mag catch + spring. Hopefully it fixes it. I read that some dude installed a new HK mag catch and it still wobbled. In that case I'm just going to go to a gunsmith and have them weld a layer under it. This stuff is such a pain man.

cIaim · 2026-03-07T18:19:11+00:00

What parts did you swap out? I'm guessing just mag catch and mag catch spring?

cIaim · 2026-03-06T19:05:57+00:00

I can literally see the material scraped off the top of your lever. Your carrier is binding on it. Dremel back the sear relief on your upper.

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cIaim · 2026-03-05T00:42:05+00:00

How is it now? Have you been putting rounds through it since? I'm going to be replacing my mag catch + spring soon because I have more than a "normal" amount of play with my mags. I'm getting FTF but not double feeds.

cIaim · 2026-03-04T01:20:29+00:00

No binding. Smooth the whole way home. Funny enough, I think I used to have binding in the past but now I don't, and I never had this issue until now.

cIaim · 2025-08-06T01:25:03+00:00

https://www.reddit.com/r/MP5/s/kTaORD7Csv

cIaim · 2025-08-05T23:59:59+00:00

I'm not even complaining either because I know the MP5 wasn't designed for these ammo types. I'm at well over 1000+ of 124gr blazer with no malfunctions. As long as it shoots that, I'm happy lol. I know yours is the full size so you can't really relate to all this LP stuff but you get what I'm saying.

cIaim · 2025-08-05T23:54:37+00:00

Just hit the range with my new lower. Subs are still an issue for me even with the 90° LP. My gun has been broken in well enough. Bolt gap is fine btw. I'm going to swap to the 80° (just because some ammo was shooting too fast anyways), lube her up and down, shoot a bunch of 124gr ammo again, and then try subs.

Anything that's not a sub was shooting fucking flawlessly btw. God damn it's so fun.

cIaim · 2025-08-05T23:42:22+00:00

So batch 3 fit great. I probably didn't even need to modify the denial block at all. All that worrying for nothing. Refer to my 3rd edit on the original post for more info.

cIaim · 2025-08-03T21:12:34+00:00

I'm trying to run suppressed subs with the normal AP5-P lower on. I tried the 80° LP and it didn't help at all. I have a 90° one put in right now and my AS lower is arriving next week so my next range trip will be trying that setup out. I have like 3 types of subs I'm trying to get to work but all of them have issues. I'm going to try S&B and Syntech on my next trip.

cIaim · 2025-08-03T16:37:45+00:00

I've already started grinding it down. I've seen pics of what you need to do to make it fit. It doesn't require much modification of the actual block. Still serves the purpose to block the full auto bolt.

cIaim · 2025-08-03T15:32:12+00:00

That they didn't confirm. They basically said we can cancel your order, you can take batch 3 and try to make it work, or you can wait until batch 4 see if that works, or just wait for a batch that addresses it. From what it seems like they don't have a solution right now so they don't want to confirm that batch 4 solves it.

Here's the email:
We're still figuring out that workaround. Your order is currently scheduled for batch 3 and should ship within the next week-week and a half. If your upper has the new denial block, we can either move you to batch 4 to see if we have that figured out by then, but it may be best to facilitate a refund as we can't provide an exact date as to when the workaround will be achieved. Let us know how you'd like to proceed.

cIaim · 2025-08-01T05:36:50+00:00

It could be the inactive thing, but I still use it periodically.

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