Inside the back of the SDP w/ pics

As most of you know the SDP has a permanately attached butt-plate (as I refer to it as) with a QD sling swivel attached. Other than that it looked like any other Kriss carbine. I am waiting on my Form 1 to come back so I can SBR my SDP. I plan to add the stock kit sold by Kriss once the stamp comes in. How to attach the stock to the SDP was eating at my brain-matter. So curiousity got the best of me. I wanted to see if the stock sold by the manufacturer would actuall fit the SDP with none, zero, no modification to the actual firearm. I searched for days trying to find out exactly what was going on underneith the SDP's butt-plate, but as most of you know indepth info in the manufacture of the V is somewhat....uh-hem...sparce.

So out comes the tool kit, or actually, the Kriss went to the garage.

I was told that the SDP uses a "bolt" to attach the butt-plate versus a standard push pin like the takedown pins that hold this gun together. Sure enouh, its a shoulder bolt.

Heres a few pics to help anyone searching get a better of the inside of the SDP:

Heres the actual components. You can see the shoulder bolt and the small machine screw that goes into the feamle end of the bolt.



Another shot showing some more of the components:



Heres whats inside, and you can see a loosly fitting silver metal insert thats threaded to accept the faux stock folding button via a large 5mm allen bolt. I believe this piece actually fills the void that would also serve as the catch for the side folding stock release's "hook". That metal threaded piece is inserted from the top of the reciever (I believe). The threaded hole goes all the way through the metal insert and you can see a polymer waill behind it which leads me to believe it is sealed seperately from the rest of the upper receiver and to remove would require removal of the top picatinney rail section, easy enough. :



This pic shows the SDP butt plate reinstalled using a standard takedown pin, so you know it will work:



I reassembled the SDP back to factory configuration until the day my stamp shows up. Nothing about this was illegal so dont worry about that. I never once turned the SDP into a "rifle" during the process. But you best believe that when the mailman shows up Ill be ready with parts and armed with the knowledge to do my own SDP to SBR conversion.

I hope this can help answer questions for someone like me that couldnt find much info.

cool. I think id rather trade carbine for a SDP, then send off for the SBR, rather than the other way around. You can enjoy a can on your kriss while you wait and financially its cheaper than going crb to SBR

it is cheaper to SBR a pistol than a carbine. I got quotes from Kriss on both routes. For Kriss to SBR a carbine it was well over $400 and a 3 week wait. For Kriss to SBR a pistol it was in the low $300 and a 3 week wait. And thats after upto a 6 month wait for the ATF to approve the conversion. For me to do the SBR conversion on my pistol it will cost under $100 in parts and about a 6 pack's worth of garage time.....

Excellent info and great pics , now I cant wait for you to get
Your stamp to see the finally sbr build

Can someone with a folding stock rifle please post a pic of the back of the receiver with the stock folded similar to the last pic posted above???

Certainly, when I get home. It is a gaping hole. Imagine the metal plate not there. Beltfed, when you make your SDP into a SBR, would you mind selling me your butt plate? I want that V shaped button delete that yours has. Since I cant have a "folding stock" in NY I have pinned my stock.

SolScud, I dont see why I would need the butt-plate anymore. So sure, I guess I'll let it go. It may be a while though. When the stamp comes back ill let you know.

Thanks. I took a picture of the back of my KRISS but I left it at home in the camera. Sorry. Will post up tonite.

Sorry for the delay. Here you go.

Thanks, thats pretty exactly the same as the SDP. Theres a small plastic on top of the SDP that is retained by the picatinney rail. It must be removed to remove the threaded metal insert in the sdp. Should be pretty easy as it doesnt look to be glued in.

Thanks again. Ill do a complete writeup of the conversion when the stamp and parts are all here.

if I would have known this I would have bought the pistol 1st and done the
SBR wait

Yeah, it is easier but I did not realize it was this easy.

Wonder why the guys at KRISS wanted to charge $300 to $400
For the SBR job.

I think part of it is filing the BATFE paperwork, shipping, probably a "refresh" and test fire, base 'smith "bench labor" charge by the hour, etc. No idea if they do the conversion if that extends the warranty, but if you do the conversion yourself I believe it voids what you have (if any left).

Dont forget about the engraving of the receiver.

Engraving can be done by anyone capable of doing it to ATF specs (3/16 high and .003 deep I believe). I had my last ar15 engraved at the local trophy shop. Cost me $25 and looks just like the factory did it. This KRISS will be done the same way.

As far as warranty I have email confirmation from KRISS that the end user ( you and me ) can do the conversion without affecting the warranty. Just to be sure I sent the same inquiry to them again and received the same answer from a different employee. So I actually have two emails from KRISS stating I can convert the SDP to SBR myself using the factory parts with no affect on warranty.

They probably charge for parts, conversion labor, paperwork preparation and remember they have to prepare a Form 1 and wait for approval and then prepare a Form 3 and wait for that approval and then finally send your gun back to your class III dealer. $400 seems about in line for all that if you consider it.

Thank you for your post. I have a California model with fixed stock and want to convert it to folding stock. Your post and pics have greatly help me figure it out how to do the exchange. Just need the push button. Haven't found it available anywhere. If you know where I can buy one just let me know.

One question, my Kriss stock hinge pin doesn't have a screw head. How did you remove it?

The California models have a hex screw loctited in place. Then the hex hole is drilled out smooth. You need to take a Dremel and slot the hex head to use a screw driver and unscrew the head out.

I had to drill it out. The Dremel trick didn't work for me. The drilling just took couple of minutes.

This is an awesome post! I was having the same thought about a DIY job on the sling point removal for a stock conversion. And this post swayed me to buy the pistol version, so it can be SBR later on.

Thanks!

Can anyone confirm how to remove the picatany rail, I got my forms back and made great progress thanks to this thread, but am stuck at removing the metal block from the rear of the gun. Before I get a block of wood and just start wailing on the rail with a hammer I thought I better ask first, I also did remove the screw at the front of the top rail but that sucker doesn't want to budge.

There is a pin the runs perpendicular to the rail. It is located towards the front under the rail. You have to punch it out.

buddybaja wrote:There is a pin the runs perpendicular to the rail. It is located towards the front under the rail. You have to punch it out.

Correct. Here is a link that will help... see page 8.

http://www.kriss-usa.com/ressources/dealers/armorer-s-course

It was mentioned in another thread that you can make something similar to nylon stock by cutting off a piece of an inexpensive kitchen cutting board.

But dont cut up your current cutting board.... before telling your wife. Lol

Thank you very very much, I'm going to finish my SBR today!