A fellow messaged me the other day and asked what options he had to replace the light fixed stock on his SDS 12 gauge shotgun. I told him that he has a lot. The rear of an SDS is very similar to an AKM or AK-74.
The rear piece that holds the stock in is called a “trunnion” they are what provide the real strength in the sheet metal receiver. The stock is held in place by the two screws you see. Be sure to use a blade screw driver bit that completely fills the slot. You can see that whomever installed the screws at the factor did not do this and slightly deformed both slots by using an undersized screwdriver or blade bit.You may need to use a wood dowel, or whatever you have handy, to tap the stock out. I like using a hardwood dowel because it doesn’t bend or scratch things all up.I used a Rifle Dynamics adapter that lets you convert from the AK-rear to an AR/M4 buffer tube. Both the Rifle Dynamics adapter and the one sold by PSA are very well made.
With the rear stock removed, you can use any AKM/AK-74 traditional wood or polymer stock that you want or adapter to use an AR-style stock. Read up online before you buy because there are tons and tons of options and combinations for you.
I hope this helps you out and here are a few examples for your consideration:
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David told me they did have a few quality control problems early on and that he wanted to replace my four magazines. Note, David said they have sold over 3,000 magazines with just a few problems and given that I haven’t heard or read about others having problems, it must have just been bad luck for me. At any rate, I was impressed that he reached out so quick and a few days later the replacement magazines arrived.
To make sure I didn’t have further problems, they had opened each package and tested the followers, which I appreciated. Let me tell you, the difference was night and day. The replacement magazine followers were much looser as they approached the top of the mag and felt great from the start. Exactly what I would normally expect. Of course, this then begged the question of how would they perform?
About a week after that, I finally got a chance to take the Lynx and the new magazines to the range. I could tell the Lynx was still wearing in. Whenever you have a weapon with parkerizing, it is to be expected. We put about 25 rounds of 2-3/4″ Remington 00 buckshot through it the first time and then I put about 70 more through on this trip. I’d say somewhere between cumulative round 40-50 (meaning from the fist session and this one), the SDS really started to smoothen out.
How could I tell? It was cycling faster and it was kicking rounds out very aggressively so I turned the gas port down from wide open to the third widest setting. I bet I can turn that down again for these higher-power rounds in the near future.
Those 12 gauge rounds are stout. It’s been years since I shot more than 25 in one session so I was feeling it. You’ll also notice that my JMAC brake loosened up. I had hand tightened the jam nut and forgot to secure it with a wrench. I fixed that problem as soon as I got home.
At any rate, the new SDS 10 round magazines worked great especially once the action started smoothing out. I tried them all the way full with 10 rounds as well as starting with only five rounds. I also fired both buck shot and some Brenke slugs. Thus, I’m happy to report that the SDS magazines appear to be good to go.
There is a good lesson here for all of us – including me – definitely test your gear before you need to rely on it. Thankfully this was just me getting embarrassed by my buddies at the range razzing me vs. a critical situation.
Now, I next need to point out that I took the CSSpecs magazines with me also and all they did was jam so I need to contact those folks and work on them next.
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I placed my order on their website and within a week receive to magazines that were built like a tank. I had a problem with some of the plastic SDS 10 round magazines in terms of the follower going all the way to the top. The Csspecs follower shot up in the top so fast I think you could take off a body part 🙂 just kidding but it is very well done.
You have to love a magazine that is so heavily made it can be used as a defensive weapon all by itself 🙂 Seriously, Csspecs makes some wicked mags and they tell you right up front that you may need to do a bit of fitting and I did.
Fitting The Magazines
The magazines come with a small instruction pamphlet for fitting that makes perfect sense to anybody who’s ever had to fit AK magazines. Step one is to make sure that the magazine fits correctly from front to back. If it does not you trim a little bit off the back tab of the magazine.
In my case it set right in. You can see how the mag stops are coming right against the bottom of the receiver. This is good! If I did need to trim it, I would have carefully filed a bit and tested over and over until the mag stops contacted the receiver, polished the surface and applied cold blue per the details in the next step.
In my case, the magazine locking lever would not engage the mag’s tab at all. That means that little tab was too thick and needed to be filed down. This is really a situation where you want to use a fine hand file and take off a little bit at a time and test – don’t rush this. Take care to maintain the slight angle. This helps with the lock up. Do not make it flat and try to keep it as straight across as possible.
I can’t stress enough, take your time. The above was done with a single-cut file where one edge was ground down so I can make cuts like this with out damaging the surface. You can sometimes buy files like I show below with one or both edges left plain. In my case, I used my belt sander to remove the teeth on that side.
This is not a situation where you want to rush. Take a little bit off at an angle and test over and over. It probably took me about 5 minutes per magazine. You want the magazine to lock into place firmly. If it is really loose I would recommend welding some material back on and fixing it.
After the filing, I did use a fine rubber abrasive polishing but in my Dremel to smooth the surface out so the lock up process would be smoother.
After I had the fitting correct, I use the little bit of Brownells Oxpho blue liquid on Long dobbers and blued the surface followed by some oil.
That is all there was to it. I hope this helps you out. Kudos to CS specs for making some very nice magazines. These things are rock solid and I may very well pick a couple more up at some point.
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Well, Scott, Brooks and I went shooting a few weeks back. I was really excited to take my new SDS Lynx out and I had bought four brand news SDS 10 round magazines that I took out of the wrapper and threw in my range bag. That turned out to be a mistake. The photo above is of Scott trying to clear yet another jam from the Lynx with one of the 10 round magazines inserted – they had feed failures constantly.
One of the things I was told years ago was to test everything before you rely on it. Now granted I was just going to the quarry to shoot with my friends but I really should have tested those magazines. Of the four, only one kind of worked. The followers were all hanging up about an inch from the top. The five round SDS magazine that came with the shotgun ran great but five founds at a time is not the most exciting thing. It was frustrating and disappointing at the same time.
The Lynx and the mags went back in the gun case and I felt pretty stupid for not checking the mags before going. On the other hand, they were brand new and should have worked. I was more than a bit miffed also – clearly there was a manufacturing issue, Followers should spring to the top of a magazine like a rocket – not get stuck part way down. A person should not need to buy magazines and then tune them inside – getting them to fit an AK-style weapon, sure that happens all the time, but not needing to redo the internals.
In the following photos notice how the followers are not all the way to the top compared to the small 5 round magazines.
At that point I made a decision – the SDS magazines really did look well made and rather than send them back, I decided to tune them and document what I did to share with others.
The Lynx shotgun uses Saiga magazines so this design is common and writing up what to do might very well help others out. So with my mind made up, it was just a matter of finding the time to do it.
A couple of weeks went buy before I could dig in but finally the time came. I’m going to try and show you what I found and explain what you need to do to correct it. You’re going to need a Dremel (or similar rotary tool), rubberized polishing bits, felt/wool polishing bits, and a plastic polish – I use Plastix a lot but even toothpaste would work. Yes, toothpaste is a very fine grit polish – you can even use it to polish plastic headlights.
Disassembling a SDS Magazines
The SDS magazine comes apart just like any AK magazine – you push the button on the bottom with a screw driver and slide the floor plate off of the magazine body. Now take a look at it. It can only push off one. All of the magazine Parts in the SDS can only go one way.
So push the button down and shove the floor plate in the direction of the opening. You may need to use a small Mallet or something hard to give it a little bit of a whack to get it started.
Now once you get that floor plate off the rest is going to want to spring out so use your thumb to keep it from flying across the room or in your face.
Fixing The Problem Area
The problem area in the magazines seem to be in the upper inch to inch and a half. You’ll see a mold seam that needs to be erased using the Dremel tool with the rubberized abrasive tips as well as it being tight in general all the way around.
So the first thing I did was to use a small rubberized abrasive tip to erase the mold seemed entirely that runs around the inner area of the magazine. In the next two photos you’ll see a shiny protruding lip inside the magazine that is just above the follower — that is the mold seam I am speaking of. It’s important to note that the follower is binding even before getting to that seam.
I used a small rubberized fine abrasive tip in my Dremel to literally erase the mold seam flush with the rest of the mold body.
At this point I blew out the magazine body with compressed air and the overall fit of the follower to the magazine body was just too tight. It and the body needed to be thinned a bit – not a bunch, just a bit.
In terms of the trimming, I would definitely recommend that you use the abrasive tip to remove just a little and test over and over. I can’t stress this enough – don’t try to do it all at once. As the saying goes, it’s easier to take more material off than to try and put it back on.
I wound up switching to a bigger rubber abrasive wheel when I did the follower and as far as I could reach in with the bit on the Dremel. The bit is still fine, I would not recommend using anything very aggressive. I used this bit on the follower and the inside of the magazine body. You just need to take a little bit of material off. I went all the way around the magazine body and the follower in that top area. You’ll see just below the scene there is a little elevated area inside the magazine that guides a follower up into position that is too tight.
Now I found I needed to do a second step to really smooth things out. The abrasive bit leaves a rough surface and the next thing I did was to use a felt bob/bit with felt on the end in my Dremel along with Plastix polish to finely polish all the surfaces. I tried skipping this step with a couple of the magazines and the end result was so much better that I went back and polished the surfaces I worked on in all of the magazines.
The polishing with the Plastix really made a big difference and I would recommend you do it as well. You could tell the parts were smoother. Definitely wipe everything down and do not leave the grit in the magazine.
Next, I sprayed the Dupont Teflon dry film lubricant in the magazine body and on the follower. I would not recommend using oil or anything that leaves a residue that dirt will stick to. Instead you want something that is going to leave a dry film behind. This really fixed everything once and for all.
9/21/23 Update: Dupont no longer sells a Teflon spray due to environmental and health concerns. They sell a ceramic-based spray now that I use instead.
I then reassembled the magazines. As mentioned the parts can only go one way. I never took the spring off the bottom plate so I didn’t have to worry about its orientation.
I went ahead and did one final spray of Teflon around the follower and let it run down in. While it is still a liquid, the lubrication will not be very good. You need to let it dry. In my case, it shot up like a rocket. Job done.
End Result
The magazines all seem to work fine now. I think the problem was a combination of the mold seam and that inside area being just a tad too tight. I hope this post helps you out. Small side note to SDS – you really ought to fix this.
10/15/18: First thing this morning SDS reached out to me and is sending replacement magazines. I will test them and report back. They have sold over 3,000 magazines with just a few problems so I might just literally have a bad batch.
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In the first post, I documented my favorable first impressions of the SDS Lynx 12 shotgun. After posting, at least 10 gentlemen have come forward stating how much they like their Lynx 12 shotguns and nobody reported any problems. In this post, I’ll write about taking the shotgun apart in order to install my planned customizations, which will be in the next post.
Call me old school, but the first thing I did was to read the manual 🙂 The next thing was to hose down the hole shotgun and wipe it down to remove all the odd smelling rust preservative. I really didn’t care for the tacky feel to be there while working on it. Once removed, I sprayed on Rem Oil to prevent rust while I was working on it. Rem Oil is nice and thin and doesn’t have too much of a smell. It’s my go to for situations like this. If you do remove the preservative, just be sure to apply whatever oil or rust inhibitor you prefer.
Removing the Dust Cover and Recoil Spring
The dust cover comes off by pushing the release latch (the little button that sticks up) on the recoil spring and pushing the whole assembly forward while lifting the dust cover up and off the receiver.
You’ll notice I have the Lynx sitting in my Tipton vise. I’ve had it for years and it really makes working on long arms way easier.
With the dust cover off, you can get a good look at the recoil spring assembly. Some guys will call this the operating spring or the return spring but basically it absorbs the energy of the bolt carrier assembly coming back after firing and then when the spring has enough energy, it pushes the bolt carrier assembly forward to then cock the trigger and strip a round off the magazine and go back into battery.
Compared to a regular AKM, you will notice the release latch and the rubber buffer assembly at the rear. I find the use of a buffer interesting. Normally the spring should absorb the energy and my bet is that the designers put it there in case the user either adjusts the gas regulator such that the system is over-gassed and the carrier comes back with more force than the spring alone can handle or they put it there just in case of a round that generates more pressure than what the spring can handle but the gas regulator doesn’t exactly have the right setting — imagine needing a gas setting of “3.5”. At the third position there is too much gas but at 4 there is too little. I have little doubt it is a good idea. I’d recommend to keep a spare buffer on hand and inspect the one in the shotgun regularly. It ought to last a long time under most conditions but the buffers are dirt cheap.
To remove it, push forward on the rear part that normally protrudes from the dust cover. It should slide forward in the slot that holds it on the trunnion until it is free and you can then lift up and pull back to remove the assembly from the bolt carrier and shotgun overall.
You will also note that the designers made the recoil spring assembly two parts – the rear is a tube like an RPK or older milled AKs with one spring. There is then an additional cover that rides on that rear tube and normally closes the otherwise enlarged ejection port in the dust cover. In front of that is then a floating spring.
Removing the Bolt Carrier Assembly and Looking Inside the Receiver
First, remove the bolt carrier assembly. It slides to the rear of the receiver and can then be lifted up out of the receiver. Note – it must be fully to the rear or the receiver’s guide rails will retain it.
It’s interesting how the bolt carrier is short. In the gas tube, which is pinned in place, is a disc, that some call the “gas puck” or just “puck” which is the gas piston. Unlike an AKM, the gas tube is held in place by the gas tube seat (it reminds me of a rear sight block in a way) that would need it’s retaining pin to be punched out to be removed. When you tilt the shotgun forward and back, you can hear the puck moving back and forth in the gas tube. I didn’t take the gas tube assembly apart but it looks straight forward enough.
The carrier is holding a really massive bolt. It operates very much like any AK – the bolt head has a cam that travels through a slot in the carrier that in turn rotates it into or out of battery.
By moving the bolt head to the rear, the cam can be rotates out of the slot and the bolt head then removed from the carrier.
Look at the size of the extractor!
Interestingly, the firing pin has a spring pushing it backward compared to the floating firing pins you normally find in an AK rifle. In this photo you can see the tail of the firing pin pushed out the back of the bolt body by the spring.
Looking down in the receiver was a very typical looking fire control group. Note, it has been tweaked slightly to work in a Saiga or Lynx so if you want to replace the fire control group you will need to either buy one made for the the Saiga or Lynx or you will need to make some modifications.
Normally I replace the fire control group (FCG) with a US made set but the Lynx’s trigger is surprisingly decent. Not great, but decent. It was gritty from the parkerizing and lack of use but I figured grease and time could cure that. I may well swap it out in the future but time will tell.
The Pistol Grip
Now I did run into one surprise that I did not expect – see the grip nut below? I figured it would be a regular AKM nut meaning threaded for a 6mm diameter x 1.0mm pitch screw. It’s not. I did not expect this but the grip screw is actually smaller than an AK’s. The screw is actually 5mm diameter x 106mm long. I did not bother finding out the pitch by the way because it would not be staying! Instead, I focused on the hole in the receiver – it was the same size as a normal AKM grip nut. Whew – Problem solved. I would replace it with a beefier AKM nut and one of our high-strength alloy grip screws (I’ll detail that in the next post).
To remove the grip, there is a blade screw head on the base. Simply unscrew it and remove the grip and the grip nut.
Removing the Buttstock
The plastic buttstock is held in place by two machine screws on the top of the rear trunnion. The rear trunnion is an AK-74 forked style with the front portion open. The stock with its lightning cuts on the side harks to the 74 also other than having a recoil pad thicker than what you would find on a 74.
Given how front heavy the shotgun felt, I was not surprised to find out that the buttstock was actually hollow. The Chinese installed threaded inserts for strength. I think that is commendable actually. The fit of the buttstock to the receiver is both well done and very tight. This is what will bear the recoil – the screws are just there to hold it together.
Because of the tight fit, I secured the rifle in my vise after removing the selector lever. I then used a wood dowel and hammer to tap on the lip of the stock to push it backwards out of the receiver. It really didn’t take much force to get it out. For those of you who have tried to get an old varnished AK-47 stock out of a receiver, you know exactly what I mean and the Lynx requires just a small fraction of that.
The Forearm
The sporting looking forearm is held in place by a 5mm diameter x 11mm long screw. Unscrew it and push the handguard forward past the gas tube and then pull it off the barrel. Mine was a tight fit so I did need to pull it off the barrel and not just lift. I did use a small piece of wood and a hammer to get it started out of the receiver.
Done
At this point, I had the shotgun all the way apart other than the muzzle cap. I left that on to protect the threads while I worked. The next blog post will detail the customizations and a few surprises that happened along the way.
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