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Muffman

Rifle Dynamics AK to M-4 Stock Adapter

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I purchaced one of these for my Vepr 12. Not 100 % but think it is drop in ready!!!

 

DSC01990_zps81b910f6.jpg

 

I say not sure.. well because I'm not sure. I have never installed one of these on a normal AK and I can't find a video so not sure if I'm OCD or it is good to go. This first pic is with the first piece installed. This is the piece I thought I was going to have to sand or file to fit. But it is swimming in the Vepr 12 receiver. Clearly they designed this not to fill any AK make's rear trunnion completely. One thing I am unsure of though is how deep it sits inside. But seems like any make would be the same in this department? Any thoughts on this?

 

DSC01992_cr_zps489f7919.jpg

 

Here is with the second piece installed. Because the first piece sits in so deep the two parts never make contact. There is a slight gap between the two. Once again, not sure if it is designed that way, or if this is the problem with running an RPK receiver. However I thought the only difference was thickness, so not sure why that would chance how deep the first piece sits in and how the two pieces would make contact. Once again, any thoughts? Either way the screws easily reach from the second piece to the first piece, And the back of the second piece is fully supported by the rear of the AK receiver all the way around. So even if it was designed for the two pieces to make contact, I don't see how it would be a deal breaker for them not to, unless it puts stress on the screws cause there is a small gap? Sounds reaching.. think I'm being OCD and it's good to go. Just add blue loctite and call it a day.

 

DSC01993_cr_zps8585ab36.jpg

 

I mainly bring these issues up because their website lists all these AK's the adapter is not compatible with, and don't get why. Not an AK guru, but maybe cause all of these models either don't have a rear tang cause they are folders, or the receiver is not a 90 degree cut, so M4 stock would be wonky and pointed up or down at an angle.

 

Also, I ordered a buffer tube but it's not compatible with the Rifle Dynamics adapter. Doh. Ordered a Vltor shotgun buffertube not thinking. The Rifle Dynamics needs a standard M4 tube for the tang to go inside the tube, and Vltor shotgun buffer tube has a metal wall filling in the begining of the tube since shotguns can not use a buffer. Either going to drill a hole for the tang, or send it back and get a standard tube....

 

Anyways.. thought I'd share. This might be a new big thing for vepr 12's...

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Mind posting a pic of the forward face of the rear piece?

 

I'm a little disappointed that It doesn't fill the inside of the receiver. Might be time to get some practice with the tig.

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Muffman - First, thanks for posting this. I have been considering this adapter for my AK rifle or my Vepr 12. Or both.

 

The gap between the two parts is interesting, not sure what to make of that. If the piece that receives the buffer tube sinches up tightly against the receiver I am not sure it's a huge issue. However, I would be surprised if it was designed to have a gap. I wonder if the vepr and ak vary in the depth of the tang on the receivers? Or maybe they did make it that way to be adaptable for variences in the depth of the tangs on various AKs.

 

 

Do you happen to have an AK you can try this on or someone near you that does?

 

I have both, but I am in STL Missouri.

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EDIT:

 

The more I think about this the more I think it would have the same gap between the two parts of the adapter in my AK. Here is why I think that: Both my AK and a Vepr 12 I have - each have a Vltor Buffer Tube Stock adapter for AKs which has a slot for plastic cover that blocks off the back of the receiver. It is perfectly aligned and flush with the back edge of the receiver on both firearms.

 

So It appears the tang depth and position of the tang screws is essentially the same on both models. If you have a gap on your Vepr-12 with this RD unit, it would have the gap on an AK as well - which leads me to believe it was designed that way.

 

Edit x2:

 

The tang screw hole on the vltor buffer tube adapter for the AK for the inside of the receiver is oblong and adjustable, however, the tang screw hold outside of the receiver is fixed.

 

Either way - I think that gap on the RD would exist on an AK or a Vepr and is apparently on purpose.

Edited by ec4321

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I'm with you in thinking it is ok, and more then likely designed this way. Unfortunately I don't have another AK with a tang to test. I'm going to email Rifle Dynamics and check with them on this as well. However I will be out of country for a month so not sure when I will be able to update on any findings. I am very excited with this product thus far and think many should stay tuned. If this all works out, a drop in ready product that requires no modding to the receiver or product, and can accept M4 buffer tubes and even M4 sling plates such as the Magpul ASAP is pretty huge imo. Also opens the options for running an Enidine buffer tube, of course hoping that it doesn't effect reliability. But I've seen Saiga 12's with Enidines.. so good chance will work...Fingers crossed this adapter works out. But can't test it out for a month, and have to get another buffer tube since the Vltor shotgun buffer tube is not compatible with the Rifle Dynamics adapter. sad.png Going to get a normal Vltor buffer tube, gave up idea on drilling. The tang fits in there very tightly and tube needs to be completely hollow.

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I called them the other day after seeing this product and they said it will not work with a VEPR 12 and is not recommended for this use.

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On a side note, can you comment on how you like that pistil grip? I like the AR looks and functional idea of it, but was curious how it felt on an AK,

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This was the reply I received from rifle dynamics a few days ago.

 

"Mr. Boone,

 

Thank you for contacting us at Rifle Dynamics. Please check out the notes under the stock adapter on our webstore. It should be strong enough for the S-12, but I don't believe it will fit the VEPR or RPK.

 

 

Thanks,

 

A.J. Adams

Rifle Dynamics

07FFL/SOT"

 

 

When I spoke with them they did not recommend it since it was not designed for the firearm and the sentiment echoed the above statement that they believe it may be strong enough, but no certainties, and that they did not think it would fit properly.

Edited by menace667

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Based on the pictures and measurement comparisons between my AK and my Vepr-12, frankly, I am not convinced the person that responded to your email from RD knows what they are talking about.

 

What about it won't fit the Vepr or RPK? Clearly the bulkhead has plenty of clearance to fit inside the receiver. They might be referring to another set of dimensions, but unless they are specific, I am skeptical because they may just be playing it safe and not really know if it would fit or not. I also know from measuring the distance between the tang screws and the rear edge of the receiver on the AK is the same as the dimension on the Vepr-12.

 

I have one on order and will try it in both my AK and Vepr-12.

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The outside M4 adapter part is excellent, but the inner mounting block part is sorely lacking in design strength...pitiful.

 

It doesn't fill the receiver cavity, and it has an air gap between the 2 parts with only 2 small screws providing ALL of the support between the 2 pieces. I'm pretty sure I could take that stock adapter over my knee and break it in half like a tree branch.

 

I'll probably have to make a better inner block myself and see if I can weld it into a one piece unit.

 

It has potential, but in it's current state it's all show and no go IMO. I should have kept my mouth shut on it until I got one in my hands.

Edited by Thor's Hammer

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I received my Rifle Dynamics Mount.

 

I fitted it to both my standard AK Rifle and the Vepr-12. The fit is essentially the same, and as is described in this thread. Although, I believe it have a very solid foundation. Essentially you cinch down the buffer tube adapter to the back of the receiver very tightly. Any recoil that doesn't damage the receiver itself will have no effect on this unit, the receiver will simply transfer the energy directly back into the adapter, to the tube, to the stock and to your shoulder.

 

I wouldn't use my butt-stock like an axe, no. But I don't think the two tang screw config of any AK will stand up to that abuse.

 

I like it.

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Thanks for the update ec4321!! I'm with you, I like it. The adapter is far from suspect imo in terms of durability, but it would be nice if it was more beefed up. I don't think it could take too much smacking against a tree, however I think there are a lot of aftermarket stocks that could not take that abuse. Not sure when you would put it to that abuse even. However, it is an AK variant. And I, like most, enjoy the thought of it as indestructible. I don't get to play it with it more until I get back in a couple of weeks. I should have a proper buffer tube by then to test it out more. I'll post some more pics when I get back if anyone would like to see a complete setup with a Magpul ASAP plate.

 

To menace 667: Imo the MFG engage ak grip is the best grip on the market for the ak platform. Great ergonomics, very similar to M4 style grips, but no need for an adapter. I have one on another AK and it is perfect. However on the Vepr 12 it causes the safety to dig in the top of the hand very badly when on safe compared to the stock Molot grip. I plan on modding the stock safety to resolve this issue.

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Here are my final results:

scaQC.jpg

 

i6wF6.jpg

 

 

I like the results, allows me to mount a UBR - Thor's Idea. I have an UBR on a rifle and I like it, seems perfectly suited for this "heavy" shotty. The RD unit allows me to do that - the UBR uses a proprietary buffer tube so you have to have the buffer screw in point.

 

Specs:

Total System with stock and adapters - 1lb 13ozs. Ouch.

8.5" from back of receiver, fully collapsed.

 

CTR Stock on VLTOR Buffer for AK:

1lb 2ozs

8" from back of receiver, fully collapsed.

 

Don't have weights, but CTR on a CSS Buffer collapses all the way in which is about 7"

 

Depends on your needs....

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That is a very sharp looking weapon there.

 

I can't say I like the RD adapter though, it severely weakens the know weak point on AK style weapons. Most aks end their life when the rear trunnion batters the receiver and rivets to death. On a factory ak the stock sits against the trunnion and your body supports the trunnion when it gets struck by the moving carrier. An ak will come apart quicker if it is fired unsopported. The RD adapter can only exacerbate the problem, by not only not allowing your body to support trunnion, but also by using your body to support receiver, making each impact more forceful.

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That's a good point, Obi.

 

I wasn't aware of that dynamic.

I know the Vltor AK stock adapter would also have the same shortcoming. As would anyone that goes with the Kushnapup. I am sure there are many others.

 

The CSS might but up against the trunion, I am not sure.

 

With this one, if someone was so incllined them could sand down a block of wood to serve this purpose. It would wedge between the bulkhead of the RD adapter and the trunion. I might do so when I find time....

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Wow, looks amazing! Good job man!!

 

Like ec4321 stated, if the RD adapter has this shortcoming, many others on the market would as well, like the super popular Vltor adapter. One thing I am confused on though is what you stated Obi about the carrier striking the trunnion. I always thought if this was occurring, then it was a bad build or your recoil spring is worn out and needs to be replaced with a new stiffer one. None of my ak's have ever had the rear trunnion marks from slamming into, but I have seen many pics before of this on crappy builds or ak's needing new springs. However, it seems like this is more the norm with Vepr 12's for the carrier to slam into the trunnion from pics I've seen and concerns raised in another thread on the forums. I have yet to fire my Vepr 12 cause of my schedule so am not sure if it is striking the trunnion or not.

 

ec4321, as far as the block of wood, I'm having a hard time grasping but you have in mind. But am definitely interested and going to play with mine when I have some free time and see if I can come up with something similar.

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All I mean by a block of wood is this...

 

The factory wooden stock presumably provides the support that Obi is talking about. Take that size and shape of wood, the part that fits inside the receiver, remove the part from that wood - just enough to accommodate the part of the RD adapter that goes in the receiver.

 

It sound like, from Obi's description, the point is to support the trunnion by transferring energy from the trunnion to the stock. So it would only really have to take up the space behind the RD adapter, not really surround all sides of the RD adapter. Depends on how much work you want to put into it and the forces in place.


Thor may like to have one that fits like a glove.

Edited by ec4321

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The Vltor, does not have the same issue, on the Vltor the tube is supported by the trunnion, not the receiver.

 

If your carrier does not hit trunnion your rifle is short stroking. ideally it would just kiss it, but for reliability it must have enough energy to function dirty, crooked,and with all types of ammo, so it necessariy hits with impact.

 

I am not suggesting that your shotgun is going to come apart, and am confident it will last you a lifetime, I just don't like the idea of it, thats all.

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I like the results, allows me to mount a UBR - Thor's Idea. I have an UBR on a rifle and I like it, seems perfectly suited for this "heavy" shotty. The RD unit allows me to do that - the UBR uses a proprietary buffer tube so you have to have the buffer screw in point.

 

Specs:

Total System with stock and adapters - 1lb 13ozs. Ouch.

8.5" from back of receiver, fully collapsed.

 

CTR Stock on VLTOR Buffer for AK:

1lb 2ozs

8" from back of receiver, fully collapsed.

 

Don't have weights, but CTR on a CSS Buffer collapses all the way in which is about 7"

 

Depends on your needs....

Looks very nice.

 

i was tinkering around the house today and made a simple spacer for the adapter. The 1/8" alum flat I used was a little on the thick side and spaces the stock off the receiver by about a millimeter or so, but I think the idea is sound. If someone wanted to spend an hour wetsanding it until the rear adapter barely fits flush with the receiver I think it would look nice and moreover put the recoil stress back on the rear trunnion where it belongs.

 

I still plan on making a whole new internal piece because I dislike the 2 screws, so these are no use to me. If you or mutt want to use them I can mail it out, no cost.

20130109_221831.jpg

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Hey Thor!

 

Thanks for the offer. Let's see if Muffman would like them. I asked a buddy to mill me a filler out of Delrin, I am going to see how that turns out. If he doesn't come through and Muffman doesn't bite, I will take a look.

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I thought about delrin, but decided the potential for compression and/or distortion on such a thin part would be unacceptable. Maybe it will work fine in practice, I dont know.

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Thanks Thor, that's really cool of you!!

I've been back a few days and have had time to play with this adapter more. The issues Obi has brought up have started more concern to creep in my brain about this adapter. A strong part of me wants to switch over to running a Vltor adapter, which I already have. Sometimes I worry this adapter would be better suited for a standard ak, and maybe a shotgun is more than this adapter can handle properly. Especially after going back and looking at the thread on this forum about people concerned with how much contact there carriers or making with their rear trunnion on their V12's. Obi describes a little cute pecking kiss on standard ak's, but some people on that thread seem to describe borderline rape, if that makes any sense... I'm sleepy. Those pieces you made Thor seem really cool, but seems like both of you are still trying on an even better solution; not implying there is indeed a problem, but at this time maybe just a concern. I definitely will stay tuned with what else you two or anyone else comes up with.

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Hello Guys, I'm sorry I don't get here more often but I'm a bit busy these days. I was alerted to this thread and thought I would try to answer some of the questions posted.

 

First off, I have no engineering degree but in my life I've built a lot of structurial items. I don't claim to know it all but when it comes to the AK and it's varients I have a fair amount of knowledge of the system and how it operates. I have spent 1000's of hours testing on anything I design or build. We are know well for standing behind what we do and the reason is we seriouslly T&E our product. In the case of our stock adaptor Travis Haley also did T&E and approved as well.

 

Our intent with this adapter was to provide the customer with an adaption method that was easy to install, strong, better cheek weld and required NO mods to the gun. I believe we have achieved that goal.

 

As most know AK spec varys a lot, when spending the time, effort and $ required to bring a part to market you want it to be as versatile and successful as possible and in the case of the AK that ment a wide varience of fitment. Anyone who has ever seriously designed anything for the AK knows this is true. We wanted it to be something the end user could easily install WITHOUT having to do ANY modifications to the gun. Due to the different dimensions/machining on trunions as well as the location the trunion is riveted into the reciever depth issues are all over the place from gun to gun . To make it fit the widest varity of recievers the space will be there or on some or it would bottom out keeping the rear peice of the adapter from properly seating against the rear of the reciever which is where the installation gets it's strength.

 

On the question of structural attachment,

During testing we attached accelerometers to the rear of the reciever to measure G-force impulse on the stock, several different AK's were used including a Saiga 12. I went to my Son who has an engineering degree with my numbers to have him check my design. Accordng to him the 8/32 screws provided for the install are more than adiquite for the force being applied from the recoil of the gun. The design allows the energy from recoil to pass directly into the stock/shoulder and not on the screws.

 

On the question of durability,

We have been running one on a selectfire dealer sample that has seen about 20k rounds in training with LE, Mil, and contractors running it as hard as they run any gun. It has been dropped, guys have tripped and fallen on it from a full run and it has not broke, moved or come loose. I don't know what else to do it. We will just keep shooting it and if something eventually fails we will address it and redesign to accomodate but we haven't seen the need and don't expect we will.

 

When we were originally testing the stock adapter the Veprs available were all anglecut recievers which is why we did not recomend using them as the strength depends on reciever contact on all surfaces. The Vepr 12 pictured here (which looks great by the way) has the stock adapter installed properly and should serve him well. If it doesn't I want to know as I never tested one on the Vepr 12 and if there's an issue I'm not against tweeking the CNC program to accomodate any issue we can on future product.

 

The idea mentioned of the shims is a good one, but we don't believe is needed for a solid install, but then I have been known to put rivets throgh Ace blocks just so they would never come out. We have sold close to 1k of these with no complaints. If anyone can find a legitimate short coming , failure whatever please contact us as I want to address it. We don't put out product just for the sake of profit, many do but we don't, we seriously try to offer stuff we know for sure will give you true value for your money and not just a profit in our pockets. It's an "in it for the long run thing"

 

To Boonesteel Arms, I appreciate your comments about our product of course they would be more valid if you actually had one, installed it on a gun and tested it for yourself. As to trunion battering a properly set up AK will not have trunion battering, as mention previously in this thread trunion battering is caused by a week recoil spring or an over gassed gun. Even if a gun is battering the trunion the rivets will fail before the attachment points on the stock adapter will fail. I see that you make an adapter yourself and it even folds. I had never heard of it until this thread, looks like it could be a good unit,, if you like you can send us one for T&E we will offer our opinons good or bad to you only to use as you please. If it's a good part our endorsement would sell a lot of them for you, if we don't like it nobody has to know. Fairness in the industry Bro, it good for all of us.

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Jim,

 

Thanks for providing clarity around your company's adapter.

I installed it on one of my VEPR's and absolutely love it. It's low profile design allows the owner to pick virtually any stock out there without having to modify the rifle or the stock length.

I have over 500 rounds through mine with no issues whatsoever and would highly recommend it to anyone that wants to get rid of that short laminated wood stock that comes on the rifle.

In California we can't have a folding stock so I purchased (2) different ACE stocks. The first is an Ultralight model and the second is the Skeleton model. Both work and feel great.

Here's a pic of the rifle with your adapter and the stock installed. I'll be buying another for my second rifle for sure. Thanks for the great design!

 

P.S. I know the picture's not huge (click to see larger) but you might notice that there's no wires going to the light in the bipod grip.

Yes, there is a manual button on the grip but look closely at the main pistol grip... KellanUSA makes an AMAZING remote wireless grip for the AK and AR platforms. Check 'em out!

 

VEPR12.JPG

Edited by NightmareArmory
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R/D. I apologize for coming off as bashing your product, that was really not my intention. It is imo, one of, if not the, cleanest looking adapters out there. Nor was I claiming that the attachment points on your adapter would fail As you stated, it is the rivets that would fail first. My comment about the adapter was referring to the fact that it does not support the rivets. A shim, as Thors Hammer described, would completely fix this problem(which I hope I described as a theoretical problem, and not a frequently experienced problem). I do again apologize, it's just when I get into the mechanical theory of firearms I sometimes get carried away, it is the mechanical theory that got me so hooked on firearms in the first place. And as I stated earlier, I do believe that the shotguns running your adapter will last a lifetime it was simply the theory that had me concerned. In defense of your product, I do not feel that some of the other members concerns of the screws not being strong enough to be valid, the screws under tension such as they are are very strong, and due to the design would not receive much stress from any external forces applied to the stock, as all of those stresses would be transfered to the receiver. And if the Stock were to be used as a club, as another member suggested, I am fairly confident the extension tube would be the weakest link and not the adapter.

 

As for your offer to check out our stocks. I would be glad to send you one. I really appreciate what you guys have done and continue to do for the AK platform. It is very refreshing to see you continue to conduct yourself very professionally, when I admittedly did not.

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