I had one you need to modify the inside and cut a corner of the rubber square someone did post how to modify it on this form it's easy to do and worth it.
SP5 and HKPDW Brace Fit Issues | HKPRO Forums

 

That forum thread is perfect, thank you so much!!

I will also see what SB Tactical support says via email to see if anything has changed since last year.

 

I have the folding version arriving today. I’ll let you know how it fits my sp5.

I don’t like how chonky the telescoping version looks. It also adds several inches of length and wouldn’t fit into my backpack. I heard the sliding mechanism can scratch up the channels on the side of the receiver.

 

...I heard the sliding mechanism can scratch up the channels on the side of the receiver.

Do you know if the SB Tactical brace scratches up the channels any more than the MP5 A3 telescoping stock?

 

Personally not a fan of the end caps that SB Tactical uses. I've found that they don't fit particularly well and tend to scratch the receiver.

For a folding brace, HK parts sells this one with a polymer B&T end cap and SB Tactical brace. You could also probably buy the components and try to assemble it yourself.

SB Tactical, B&T HK MP5/SP5 Folding Brace

Get your New SB Tactical, B&T Brugger & Thomet SB Tactical, B&T HK MP5/SP5 Folding Brace for $279.95 at HK PARTS today! - HKP-19353

hkparts.net

For a retractable brace, I really like the Magpul brace, if you can find one. Great quality and fits like a glove.

MP BSL Arm Brace – HK94/MP5®

Stabilize your iconic HK pistol

magpul.com

 

Personally not a fan of the end caps that SB Tactical uses. I've found that they don't fit particularly well and tend to scratch the receiver.

For a folding brace, HK parts sells this one with a polymer B&T end cap and SB Tactical brace. You could also probably buy the components and try to assemble it yourself.

SB Tactical, B&T HK MP5/SP5 Folding Brace

Get your New SB Tactical, B&T Brugger & Thomet SB Tactical, B&T HK MP5/SP5 Folding Brace for $279.95 at HK PARTS today! - HKP-19353

hkparts.net

For a retractable brace, I really like the Magpul brace, if you can find one. Great quality and fits like a glove.

MP BSL Arm Brace – HK94/MP5®

Stabilize your iconic HK pistol

magpul.com

Wow I wish I knew about this when I ordered my SB folding brace. I just placed an order for the BT end cap / SB brace. I’ll return my SB brace when it arrives.

 

Anytime LarsBars good luck.

 

Nice wish on finding one of the Magpul ones. They came out and disappeaered within a month. I called and asked about them and they told me that they are waiting to see what happens with the Gov't due to all the FRT and 80% stuff as the braces will be coming soon too.

 

Response from SB Tactical support regarding HKPDW fit on SP5:

Thank you for your interest in SB Tactical. The modifications people were making are due to a design change on the SP5 that is not present on a standard MP5 receiver. We have since modified our endcap to no longer require the biggest modification, which was simply removing one screw from inside the endcap.

The second modification was to trim/cut part of the buffer away on our endcap. This was never necessary though does make installation easier. The change that HK made to the receiver means there is some material now that will contact the buffer and provide resistance when pushing the endcap on. You can either push past the resistance or use the indentation caused by the receiver to cut the buffer; again, not necessary, just a something some folks did for a slightly easier install.

We have been unable to produce HKPDW due to a national supply shortage with steel. We are hoping to have the resolved in the next 10-12 weeks and will start producing these braces again.

Kind regards,

The SB Tactical Team
E: support@sb-tactical.com
W: www.sb-tactical.com

 

I have the retractable SBT brace and like it. I had to twist a white plastic piece to get it to fit. No cutting involved on mine.

 

Put a little grease on the end cap/receiver, it will go on easier.

 

Wow, it's nice.

 

HKPDW-01-SB - SB Tactical HK PDW Stablilizing Brace Black HKPDW-01-SB 699618782868 | gun.deals

Keep looking and can't seem to find HKPDW in stock anywhere. Any leads on where to buy one of these would be appreciated.

 

HKPDW-01-SB - SB Tactical HK PDW Stablilizing Brace Black HKPDW-01-SB 699618782868 | gun.deals

Keep looking and can't seem to find HKPDW in stock anywhere. Any leads on where to buy one of these would be appreciated.

That thing is hideous, looks nothing like an A3 stock, and appears to add 5” in length when fully closed. And the end cap doesn’t look factory. Go with thr B&T folding brace.