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Discussion Starter #1
I've been searching all over trying to find one comprehensive, clear and precise list of the parts I would need to remove and replace with American made parts to bring my HK SP5K into compliance with 922(r). Of course, I want everything to be perfectly legal. My desire is to turn my HK SP5K into a SBR by putting a butt stock on it, etc.

Can anyone/someone point me to a post that would give me a good "how to" on what I should/can/could swap out on the HK SP5K per 922(r)?

Thanks.
 

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Receiver
Barrel
Trunion
Bolt
Bolt Carrier
Cocking Handle
Trigger Housing
Trigger
Hammer
Sear
Buttstock
Pistol Grip
Forearm / Handguard
Magazine Housing
Magazine Follower
Magazine Floorplate
 

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Discussion Starter #4
OK, thanks, and my apologies for my complete ignorance.

I just went over to HKParts and put together a parts list of potential items for 922r compliance.

Can somebody take a look at let me know if I'm good to go if I put these things on the SP5K (yes, I know I have to get a tax stamp, etc. for SBR approval.

By my count the following parts would provide SEVEN 922r compliant parts, correct (two for the mag?).

  1. HK SP5K Spec - Full Auto Bolt Carrier HK SP5K Spec - Full Auto Bolt Carrier (HKP17932)
  2. HK MP5, MP5K Cocking Handle - US HK MP5, MP5K Cocking Handle - US (MP5CHUS)
  3. MP5K Vertical Grip - USA MP5K Vertical Grip - USA (MP5KGRIPUS)
  4. MP5, MP5K 20 Round Magazine - US MP5, MP5K 20 Round Magazine - US (HKP17396)
  5. HK MP5, 94, MP5K, SP89 Bolt Head - USA HK MP5, 94, MP5K, SP89 Bolt Head - USA (HKP17939)
  6. MP5K & SP89, SP5K Choate Folding Stock MP5K & SP89, SP5K Choate Folding Stock (CMT15-01-04)
 

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Personally, I would not replace the Bolt Carrier or Bolt Head. Keep them German. When you get your sear, then you can look at replacing the carrier with a German part (or modifying the stock to work in FA).

I would go with the US-made Sear, Hammer, and Trigger, but that's just me.
 

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Discussion Starter #7
Personally, I would not replace the Bolt Carrier or Bolt Head. Keep them German. When you get your sear, then you can look at replacing the carrier with a German part (or modifying the stock to work in FA).

I would go with the US-made Sear, Hammer, and Trigger, but that's just me.
Thank you very much for your advice. I'm all ears. I have the mechanical skills of a four year old. How hard is it to replace/swap out the sear, hammer and trigger? Does sound like a very easy way to go, but ... on the other hand, if I'm going to go all in on this, I definitely want a threaded barrel for my suppressor. So...might just send it all off to an expert.
 

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I definitely want a threaded barrel for my suppressor.
If I remember correctly (and I get easily confused with this stuff), but as an SBR, adding a suppressor factors as an American part (since ATF considers sound suppressors to also be flash suppressors). Oh, and the HK flash suppressor would naturally count as a German (imported) part.
 

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HK4 (4 cal), HK45T, P7PSP, P7M13, P30SKS, MARK23, SBRs: SP5, SP5K, Z5-RS, USC/UMP
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One more question...would this work on my SP5K? Seems like a very easy way to get 5 922r parts in one fell swoop.

https://www.hkparts.net/shop/pc/viewPrd.asp?idproduct=14096&idcategory=235

That particular trigger group will not work in the SP5K without some clipping. If you want a complete trigger group, HK Parts is working on a different one which will have at least four 922r compliant parts, but it's not available just yet. Last e-mail that I received from them said they are testing the new one.

I don't think anyone has received a stamp yet to SBR their SP5K, so there is plenty of time for you to wait to get the right part. I submitted my eForm 1 in early July and had my check cashed July 5th. I don't expect to see the stamp back until March. The SP5Ks you see in SBR configuration now, are folks who had FA sears and used that stamp to make the SP5K full auto, avoiding the 922r issue.

Also, if you put the full auto bolt carrier in, you'll either have to file the nub off in the internal top of the receiver, or machine the top of the carrier so it fits. There's a previous thread where a member did that to make it work.

There are US made threaded barrels available that count. Michael's Machines installed one of his 3-lug threaded barrels for me.
 

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LOW SPEED, HIGH DRAG
HK4 (4 cal), HK45T, P7PSP, P7M13, P30SKS, MARK23, SBRs: SP5, SP5K, Z5-RS, USC/UMP
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Can you elaborate on that please? What's involved in this "clipping"?
Removing material from the trigger housing so that it will fit onto the semi-auto shelf on the lower.

From other info here on the site, if you remove too much material resulting in the trigger pack sitting too low in the housing, it may cause problems with full auto firing in that the pack sits too low for proper function.
 

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OK, thanks, and my apologies for my complete ignorance.

I just went over to HKParts and put together a parts list of potential items for 922r compliance.

Can somebody take a look at let me know if I'm good to go if I put these things on the SP5K (yes, I know I have to get a tax stamp, etc. for SBR approval.

By my count the following parts would provide SEVEN 922r compliant parts, correct (two for the mag?).

  1. HK SP5K Spec - Full Auto Bolt Carrier HK SP5K Spec - Full Auto Bolt Carrier (HKP17932)
  2. HK MP5, MP5K Cocking Handle - US HK MP5, MP5K Cocking Handle - US (MP5CHUS)
  3. MP5K Vertical Grip - USA MP5K Vertical Grip - USA (MP5KGRIPUS)
  4. MP5, MP5K 20 Round Magazine - US MP5, MP5K 20 Round Magazine - US (HKP17396)
  5. HK MP5, 94, MP5K, SP89 Bolt Head - USA HK MP5, 94, MP5K, SP89 Bolt Head - USA (HKP17939)
  6. MP5K & SP89, SP5K Choate Folding Stock MP5K & SP89, SP5K Choate Folding Stock (CMT15-01-04)
This counts as 7 parts. Remember, the 20 round US magazine counts as 2 parts.
 

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Can you elaborate on that please? What's involved in this "clipping"?
HKParts describes it best.

https://www.hkparts.net/shop/pc/viewcategories.asp?idCategory=72

That trigger housing/group will not work because the rear (tang) will not fit a K receiver (in addition to what UltraFudd described above). What you want is this.




Thank you very much for your advice. I'm all ears. I have the mechanical skills of a four year old. How hard is it to replace/swap out the sear, hammer and trigger? Does sound like a very easy way to go, but ... on the other hand, if I'm going to go all in on this, I definitely want a threaded barrel for my suppressor. So...might just send it all off to an expert.
It's pretty easy to swap the internals. A 2-year old can do it. :biggrin:
 

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Discussion Starter #16
Thank you for all the great input and information everyone. I'm all set now to proceed to obtain the proper tax stamp for my SBR-ed MP5K and for making sure it is fully compliant with 922(r).

Pretty cool that I got the MP5K at such a great price. Bonus!!
 

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Discussion Starter #20 (Edited)
All it needs is a few passes of a file to open up the area where it sits on the S/A shelf.
Have you installed one on a HK SP5K? I think I'll just wait for the one they are making for the HK SP5K, since I don't really trust myself to do a "few passes with a file" correctly without totally screwing it up. :)
 
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