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Discussion Starter #1
I have an approved form 1 to produce a suppressor and was hoping to replicate something close to the MP5SD design in which it drops the actual pressure of a supersonic round.

More to the point I was curious if anyone has a cutaway or a patent drawing of the MP5SD suppressor that I could look at for a basic reference. More in line with how and where they ported the barrel.

Was also wondering how they drop the speed with the porting exactly. From what I can tell they ported the last few inches of the barrel into a big expansion chamber and then the last 3-4 inches are standard baffles?
 

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I have an approved form 1 to produce a suppressor and was hoping to replicate something close to the MP5SD design in which it drops the actual pressure of a supersonic round.

More to the point I was curious if anyone has a cutaway or a patent drawing of the MP5SD suppressor that I could look at for a basic reference. More in line with how and where they ported the barrel.

Was also wondering how they drop the speed with the porting exactly. From what I can tell they ported the last few inches of the barrel into a big expansion chamber and then the last 3-4 inches are standard baffles?
The barrel is ported just past the threads, it looks to be about 1" from the end of the chamber. Having the ports dump into the suppressor is just for sound suppression, it doesn't create any additional bullet slowing than if it were ported to the atmosphere. By having the ports so close to the chamber, a lot of pressure is bled off before it has much time to push the bullet down the barrel. There's a pic of it and more detailed description right here on the HKPro "World of HK" page -

http://www.hkpro.com/mp5sd.htm

Nearly all silencers have an initial large chamber followed by multiple smaller chambers between the baffles. Also keep in mind that the original HK suppressor design doesn't work as well as many of the more modern conversion designs.
 

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Discussion Starter #3
Ok that explains a bit, I was under the impression that the suppressor was built quite a bit far into the handguard, and from what I understand it actually starts at the end of it (or close to it) and the expansion chamber isn't much if at all any larger than a screw on can would be. I was just looking to more replicate the porting and expansion chamber part of the design and find a nice K-baffle design for the rest of it.
 

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Ok that explains a bit, I was under the impression that the suppressor was built quite a bit far into the handguard, and from what I understand it actually starts at the end of it (or close to it) and the expansion chamber isn't much if at all any larger than a screw on can would be. I was just looking to more replicate the porting and expansion chamber part of the design and find a nice K-baffle design for the rest of it.
Right, the suppressor extends way back into the handguard, but the first portion that covers the barrel is just an empty area, which makes sense. And your plan for K-baffles for the rest of it sounds like a good idea to me, and I think how all the current conversions are done. I suppose someone could copy the cast HK one-piece baffle design, but I don't think anyone does.

I haven't made up my mind yet, but I'm leaning towards making one of my flats into an SD, and will probably do it like you are thinking of.
 

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Discussion Starter #5
yeah right now i'm just debating between K and M baffles M's are much easier to produce from what I understand.
 

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Right, the suppressor extends way back into the handguard, but the first portion that covers the barrel is just an empty area, which makes sense. And your plan for K-baffles for the rest of it sounds like a good idea to me, and I think how all the current conversions are done. I suppose someone could copy the cast HK one-piece baffle design, but I don't think anyone does.

I haven't made up my mind yet, but I'm leaning towards making one of my flats into an SD, and will probably do it like you are thinking of.
nice approach...thanks for sharing
 

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Here are some pics of my factory MP5SD for comparison if you are interested.



Hand guard off:



Suppressor off:



Barrel Ports:



End of barrel inside hand guard:



Tried to get more of the ports:



Suppressor disassembled:



The chamber area is completely hollow where the suppressor screws over the barrel ports, like a blast catch area.
The baffle stack screws into the short tube and then the long tube screws on over the baffle stack.

Hope this helps.
 

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Can those baffles be dipped in solution or...what's the cleaning procedure? Also, what is the suppressor made of? Seems like I might have read somewhere that it's aluminum. Hopefully that's not the case.
 

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A lot of handgun caliber cans are made of aluminum. It can easily handle the pressures. I held a .308 can a while back and was surprised - it must have been 1/4" walled steel pipe.
 

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How did you get the suppressor apart? A buddy of mine has two SD's and he's over 50K rounds on each. He'd like to get them apart but has been told that they're sealed.
 

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By looking at the way the holes are drilled, it puts the theory to rest that says the holes need to be drilled in the grooves and not the landes. I guess as long as they are deburred and there is plenty of the barrel left then it should be accurate. Who am I to argue w/ HK?
 

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By looking at the way the holes are drilled, it puts the theory to rest that says the holes need to be drilled in the grooves and not the landes. I guess as long as they are deburred and there is plenty of the barrel left then it should be accurate. Who am I to argue w/ HK?
I'd be surprised if they were drilled at all. They're likely created with a sinker EDM machine, so no burrs. But locating them in the lands seems like a good idea just the same.
 

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Suppressor disassembled:
The chamber area is completely hollow where the suppressor screws over the barrel ports, like a blast catch area.
The baffle stack screws into the short tube and then the long tube screws on over the baffle stack.
Hope this helps.
Another request for insight as to what you used to crack the suppressor open.
 

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Hey I have question. If this is the wrong thread I'm sorry. I am
Ordering a mp5 sd from coharie arms through my dealer but they are not a class 3 holder. I have to send it to a
Class 3 in GA. Here's the thing my ffl who is ordering it for me told me the class 3 holder is trying to
Bump the price up on my original price which coharie charged. Is this common practice when ordering a class 3 weapon?
 

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Hey I have question. If this is the wrong thread I'm sorry. I am
Ordering a mp5 sd from coharie arms through my dealer but they are not a class 3 holder. I have to send it to a
Class 3 in GA. Here's the thing my ffl who is ordering it for me told me the class 3 holder is trying to
Bump the price up on my original price which coharie charged. Is this common practice when ordering a class 3 weapon?
Some SOT's charge higher prices for NFA transfers, some a lot more. How much is he trying to add? I've seen some try to charge $100 for an NFA transfer. He can't really "bump up the price", since he's not paying for it, and you're not paying him for it. You should be paying Coharie directly. All he can do is try to charge you an increased transfer fee. Unless you are actually buying it from him and not Coharie.
 

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The Suppressor just unscrews into 3 pieces with a twist.

Now, I was told by Ralph at RDTS that a lot of police use MP5SD's are not disassembled fully for cleaning, he has to use a vice and a strap wrench to break the carbon seal.
Such was the case with this one before he detail stripped and re-finished both the MP5 and Suppressor.
My second MP5SD post sample also came out of a PD and I cannot get it open by hand.

I make sure I break the seal on the one shown after I shoot it so I can always take it apart for cleaning.
One nice sample for the collection, one sample for letting people have fun with.
It doesn't take long to form a carbon seal with the suppressor though.
 

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The Suppressor just unscrews into 3 pieces with a twist.
Thanks for posting those pics. I have a question also, does the end cap unscrew on this as well? I haven't found too much information (pictures) on how these come apart. I have always herd the same that they are sealed at the factory, and never thought about trying to open it up.
I wouldn't mind getting mine apart for an inspection and cleaning as well.

GhOsT74 ...+1 on what AviatorDave said.
 

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I don't think the end cap comes off at the user level.
I know Ralph had to fix mine on this gun as the PD had beat something with the nose of the suppressor and it was dented in.

I don't know how Ralph got it off or if it was repaired while attached to the tube, but he fixed it all smooth, never would know.

Tom
 
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