Is the MP5 SD suppressor better than stand alone 9mm suppressors?  

I know the SD uses a ported barrel.

Assuming a short barrel (MP5) with a similar sized 9mm can and an MP5SD.  Same ammo, would there be a difference?

Yes I think the MP5 SD looks great but I don’t really want to lay out the money for one.  I do have 2 MP5 and 2 SP5k so I’ve satisfied my HK fetish.  

I guess I’m asking how effective is the MP5 SD suppressor as compared to a nice 9mm suppressor.

You need to specify which MP5SD can you are asking about?  The original or a modern can?  Or is your question more asking if an integral w ported barrel is better than a muzzle can?

There are a lot of options involved and your question is way to generic to give a proper answer to.

Keep in mind the original MP5SD was designed in a time when heavy subsonic ammo was not a thing.  The barrel porting was designed to bring 115gr ammo down to subsonic velocity.  By today's standards and ammo, the original porting is WAY too aggressive and will bleed far too much velocity out of the ammo.  115gr ammo below the speed of sound has ballistics not much better than 380 ACP.

Does not matter, if he is not an SOT he cannot have either one.

So the comparison is to something current like TPM or whatever.

Inch for inch, I find the SD to be quieter (I have KAC, TPM and original B&T), but there is more blowback. The SD has cool factor, but the muzzle cans have versatility.

Apologies.  I meant brand new, modern suppressor.  Modern SD suppressor.  

I’d use it on a custom CMMG delayed blowback / ported upper.   I may even get one of my MP5s converted.  

If the performance (sound and ballistics) ain’t much better than a twist off 9mm can, then I’m not doing it.  

I can’t speak on standard MP5 suppressed vs SD but I have recently ordered a TPM can and have a SP5L I’m planning to convert to an SD. Options today for a can include TPM, RCM, RDTS, Curtis Tactical, Silencerco, and Rock Creek. I may be missing a few and I’m far from an HK expert like some of the other guys on here.

The SD has been a grail gun for me for a decade so I’m determined to make it a reality this year.

If nothing else it sounds like a cool project.

I want one of these. This is a cutaway of the "Large" suppressor designed by Qual-A-Tec and manufactured by H&K for the Navy. It's a heavy brute compared to the factory can, but it's extremely quiet.



SilentMike

Wow.  Thats a suppressor.

I have a custom suppressor, and I would do it again.  I got exactly what I wanted (not needed, but wanted).

Interesting take on a K-baffle with that diffuser face.  I’d guess much of the benefit of that huge muffler (especially for extended full auto fire) comes from the expansion chamber when you consider what a TiRant’s “simpler” K’s can do, or a CGS Mod 9 for that matter.

I know you said you want one, any leads on getting one?

I did one of these and it is really, nice.

Look into a coaxial design like the GSL Phoenix.  I have one on my PTR 9C. Very quiet with a deep tone to it.

I've fired a few factory HK MP5SD's and they were kinda gassy.  They were also noticeably even smoother than regular MP5's.
I would think you're CMMG RDB would be even smoother with an integrally suppressed setup.

I have an integrally suppressed AR9 upper that was given to me that I've been thinking about getting re-cored and then built for the CMMG RDB myself.  
However, I reload all 147GR and don't shoot much supersonic so I'm on the fence about doing it as I see the main purpose for an integral build is to drop the velocity down....but there is that increase in smoothness factor and the fact I already have an upper laying around.  

I've also been waiting to see what other delayed blowback AR9's were coming out.  I was really hoping the MEAN Arms roller delayed would come out then do an integral build for that but maybe I'll wait to see how the new JP-5 comes out.

I have regular MP5 and MP5K with a variety of commercial suppressors and a handful of integral 9MM submachineguns including an MP5SD.

My take is that integral suppressors are more quiet than muzzle suppressors especially if shooting bulk pack 115gr commercial ammo.

Now can a commercial muzzle can perform as well as an SD unit if its a larger form factor suppressor and made by one of the top companies,  and you also feed it custom subsonic ammo....sure....you can replicate the suppression of an SD, unit but at that point its not really apples to apples anymore.

I like SDs as I can run cheap (or what used to be cheap) 115gr generic ammo through them and get as good (or better performance) as a muzzle suppressor running expensive subsonic ammo.   Sure there is cheaper 147gr ammo out (like lawman or blaser)  but a lot of the cheaper 147gr was truncated cone ammo that doesnt feed well in many subguns and some of the cheaper 147s were trans-sonic in subgun length barrels.  IMHO, the best factory 147gr subgun ammo that would run in just about any subgun and was consistently subsonic and quiet was the Fiocchi 147gr FMJ round nose FMJ ammo. (9APD)

As much as I loved 9APD, it was expensive, like $350 per K and hard to find even in the best of time, when I could get 115gr for less than $200 per K from just about anywhere.   I don't know where I could find 147gr round nose FMJ ammo subsonic ammo today given current market conditions.

That said there are downsides to the MP5SD and all SD with barrel ports in general in that they usually take more maintenance to keep clean.

In terms of blowback, one of the issues with the MP5SD is unit set up with the original 120 degree locking piece that I personally think is way to aggressive.   The 115 degree MP5SD Action updated locking piece is better but I personally prefer the #16 / 110 degree MP5K locking piece in my MP5SD as it keep the bolt closed longer and reduces the fouling into the receiver and the amount of gas coming out of the ejection port.

If you don't have an MP5 at all I would suggest getting a full size with a nice subgun appropriate suppressor.   If you already have a full size MP5, than the SD is a really nice addition.

Well ain’t that something.  

Time to get a modern SD.

I have a rcm, b&t, and kac mp5sd can. They are all stupid quiet. More so than my largebore mk9 cans. And especially in full auto you wont find anything smoother or quieter. If you have the funds and want something unique, do it. I guarantee everyone will enjoy shooting it. You will not enjoy cleaning it. Im sick and tired of cleaning my mp5 sd clones so they sit the safe

Yes, I have heard that cleaning them was often and not fun.

I bet it sounds phenomenal but oof at the weight. That's one area of suppressors where I've really learned my lesson. For comparison the TPM can comes in at 14oz.

Glad to hear the SD seems to still perform ahead of the regular MP5 unless maybe throwing a huge can on there. It's been on my "list" for probably 10 years and I'm just irritated I've waited so long to get going on the project.