I have a 8.5 inch barrel running Tula 245gr, feeding it with a 20 and AR mag which fits 10 rnds of 9x39mm.  It short strokes and almost kicks the round out unsuppressed with just a flash can on it.  I would like it to run this ammo unsuppressed.  I am going to try to run it suppressed tomorrow and see if it will run.  My other thought is to use a lighter bolt carrier, these are the only things I can try with out having to order anything.  

Any other suggestions would be appreciated.  

As a last resort would opening the gas port in the barrel and gas block help with this type of round?  What are the current theories and new parts that could be used to fix this issue?




9x39mm, 7.62x39mm, 6.5 grendel

The hole in the GB is likely plenty big enough but the hole in the barrel might benefit from a ream job.  You can always go to an AGB if you go too far.  It sounds like it's either undergassed or overweight, or both.

I was wondering if the conventional AR15 5.56 rules apply to the short stroke common fixes with this particular round, as it is known to be tough to get cycling due to its low pressure. i would like to try other things before going the route you advised if possible.  I thought initially with going the AGB route, but I thought maybe lightening the buffer spring or bolt might do it.  I put this together as an experiment to see what I could change to make it work.  I test this tomorrow or sunday and see what happens suppressed and with a lighter bolt or any combination of those was well as adding a compensator to see what effect that has.

Does anyone have one working and if so what is your barrel port size? If not does anyone know what the barrel port size should be and also the length from the chamber to the port hole that works best?

Before touching the gas hole, try a light buffer, that solves my problems ...
Odin have a configurable Buffer,
https://www.odinworks.com/Adjustable_Buffer_p/os-abs.htm

Ok I will look into that

Did you have to change your spring? lighter? or you kept it the same?

Had a chance to test but only briefly due to unforeseen events, but suppressed is all I had a chance to do with a can that is not purpose built for this round keep in mind.  the bolt is coming back and ejecting the spent casing, as well as reseting the trigger, but in slow-mo video it is just shy of coming back far enough the get back behind the next round.  So, I am still in single shot mode. Tomorrow will try the other combinations

ran carbine spring and buffer, did have to open the barrel hole a little, beware the flash

I will keep that in mind

I am running a normal carbine buffer, was yours lightened? What size did you open the hole up too?

You can take the weights out of the buffer.  That might be enough to get it going.  Not a great long term solution, but it won't hurt anything.

I don't have a 9x39 but when diagnosing a DI setup I load 1 round fire and if it is not enough to lock on an empty mag then you know your undergassed.

As others mentioned step 1 would be to knock the roll pin out of the buffer and remove the weights and try again. if your still short stroking then opening the gas port would be the next step.

You could however run a krink style muzzle device which may be enough to give you the gas you need. I'm not aware of any large enough for 9mm, but i'm sure a 30 cal variant should have sufficient material to open it up to 9mm. This however would make it harder to get your suppressor on and off.

I did that last night, and tried to run it today with the lighter bolt carrier, lightened buffer, and a spring with weaker compression, it ejected with this setup and a 2 chamber MI comp, cycled 2 rounds suppressed with this setup but would not cycle a third.  I'm close, i think I might go the bigger gas port and AGB route.

Garred8787, that is a good idea i will see what I can find in the krink style, i want this to run unsuppressed if I can make it do that, but suppressed is fine also I just don't like having full time suppressed guns

when i pulled the weights out of the buffer I put one back in with a spacer and a spring to keep the weight from having a counter coup operation, should I just take everything out?

I have not had great luck in my 10" KAK upper with Tula, but it runs great with Wolf using the same mags, or on FA. I'm not sure why Tula has more issues but for me it does
The biggest factor for reliability on mine was the enhanced firing pin to handle the harder Russian primers. The extra power hammer spring didn't have any noticeable improvement

Mags have been very finicky for me but I have a couple 27 rounders that run ok at about 25 rounds

cool, I was afraid to try the ak style mag you have as I read those don't work. testing with my 20 rounders that hold ten have been working pretty well.  I ordered a couple 6.5 grendel mags to play around with as I will be looking into building a 6.5 grendel next

I got it running with my 20 round mag it runs 10 rnds reliably and very fast.  I measured my gas port opening and it is approximately .134 huge, I know but I did not do that, anyhow it is alive.  

The setup is this, I had to run it suppressed but I put the original bolt carrier back in and I'm not using the lightened colt bolt carrier, I bought one of the 300 blackout flat wire buffer springs.  I am using a buffer with no weights.

So with this setup it runs well, however I bought 6.5 grendel 25 rnd mags and they bulge at 7 rounds, would only cycle with 4-5 rnds in them, so I chucked them for a grendel build later.  So, right now I just need to find some reliable high cap mags.  I might play around with followers to see what I can do, I was about to give up on this project but it running well has changed my mind.  Now if I could get some other rounds at not retarded prices??

I ordered a PWS comp to try instead of the suppressor because I would rather not use this suppressed, so if that works then I will have accomplished what I set out to do. I like the 9x39 rounds I don't know why but it interests me.

I tested this today unsuppressed and the only change was adding the original flash can and seeing what would happen, it cycled 2 but hung up on the third round. this happened 3 times and then only single shots after that, I did this test to see if the incoming PWS comp might work and I think it will.  the suppressor I have is not purpose built for this and makes the form factor longer then I want.

If I have to run it full time suppressed then I will have to do another Form1 and if I do that, I will make the front look like a VSS.  It would be cool to make a AR-VSS hybrid.

on my DI 45 acp upper I would lube the gas rings with cherry balmz. it helps make it 100% reliable for about 200 rounds before it burns off the grease. maybe something else to consider.

Interesting thought but I want it to run without wondering when it will not.

So I decided to change everything up and I got a KS47 lower upper and BCG, so I put my 9x39 barrel and I plan to find an AK style mag to work, I ordered one from CSSPEC mags to see if it will work.  I am also waiting for an adapter so I can run my 9mm can with this.  I took the one I showed in the first pic and turned it into a 300blkout rig.

I sent you an IM. I have a ks47 and was thinking along the same Lines.  Let me know how it goes.

I responded to you and currently I am waiting for an adapter to arrive for my 9mm can. In the mean time here is a pic of my latest Frankenstein, yes I know the Bakelite mag won’t work it’s just there for looks.

Shoutout to Hughes precision who got me the 5/8x24 to 1/2x28 adapter for my suppressor, and CSSPEC mags who is making 9x39 AK style mags. Also, Pro2A tactical I bought one of their 9x39 uppers as I could not find the barrel I wanted, the barrel from that upper is what is used here. The rest of the upper went to my 300BLKOUT RIG. Thanks gun industry team!

About the adapter I know what your thinking....that can't fit a 9mm through it, but good on Hughes Percision the ID .370 yes it is cutting close with bullet diameter of .366 max, looking down the barrel I think it is a go!

Next the Mag...right now CSSPEC is the only game in town with High cap mags and the reason I changed my rig to the KS-47, lets now call it the VS-47.  I had a few guys asking about my setup using the KS-47 lower and upper, so for those guys that are interested.  The CSSPEC mags where designed for the Krebs AK version in this cartridge and not the KS-47 so you know what means....Mods must be figured out and yes I am and will be doing that for you, Yeah!  One more bit of info I was able to load 30 rnds of the 278gr wolf in this mag with ease, very nice after struggling with many others.  I called those guys and picked their brains on this mag and its fitment to the KS-47, they spent a lot of their time talking to me and it was much appreciated.

So, they explained that the mandrel they hand made has a wide front end and that is due to the 9x39 bullet needs room and the KS-47 needs more front end meat on the receiver to stay together....so I decided to modify this first mag and not the receiver.

As of this writing I have not had a chance to test with dummy or live rounds but the mag fits by taking about 12-15 thousands off both sides of the front reinforcement band, you will see in the picture below.







Here you can see the fitment scars as it is tight but I want it to be snug and eventually through use it will polish out, but most likely on the Aluminum lower, which I am fine with.



I made grip change and once I test it out I will take a pic with the final rig.  The BCG glide very smooth over the mag while inserted and I think this setup is going to run well. I know..I know I forgot the dust cover, I was wrenching crap together in my haste to want to shoot it and forgot it, I may not bother with it, we will see.



Side note: If you want to use the rail I have here you will need to modify the anti rotation devices on the front of the upper receiver as the KS-47 upper is wider than a standard AR-15 upper.

Thanks for the work.  I’m following closely

Thanks, I just got a 10.5 inch KAK barrel in to rebuild my 9x39 AR15 design, its going to look good.  I have been trying different mags in the AR platform to find a good working donor for the 9x39.  I bought 2 AR stoner 6.5 grendel 25 rnd mags. They didn't work at first but I have re-profiled the follower a little different on each and they look promising.  I hope to test 3 builds this weekend if time permits. I tried a Beowolf mag I think it could work but the round count would be low, I was able to get 20 rnds in the AR stoner 6.5 mags after modifying the follower. They look good in the mag but need testing for function.





It is bulged slightly but inserts and removes from the mag well easily, to early to say if they will work.

I got a chance to do some function testing, I focused on the pistol setups more so than the mags for today. I will start with the KS-47 build

Key setup parts;

PSA upper, lower, and BCG (KS-47)

8.5" 9x39 barrel  .124 gas port opening pistol length .750 Gas block from (Pro2Atactical)

lightweight Flat wire recoil spring (Tubbs)

unknown buffer with all weight removed

I fired it first unsuppressed using a PWS .30 cal 5/8x24 compensator which I bored out to .385 to clear the 9mm round.  this would function the .278gr wolf for 2 rounds but not a third. The .245gr Tula would fire and eject but not load a second round.  This is why it was impossible to function check the Csspec mag.

Next I used a Navy style tri-lug adapter from (In Lead We Trust) to adapt from the 5/8x24 to 1/2x28 with a 9mm through put so I could use my 9mm suppressor.  This worked great and all rounds fired and functioned.  Unfortunately, I forgot all my ammo so I was not able to do a full function check of the mag.  I did load 12 rnds and all fired with not an issue.  Most other mag loads were 3-8 rnds. I think the Csspec mags are going to work very well.

I ordered 3 more mags from Csspec the other day so I am glad this one functioned well, there is one thing to watch out for, you will need to make sure the mag seats up in the receiver for the bolt to catch the round.

Next I took the lightweight buffer and flat wire recoil spring out and put in a Spikes Tactical 4 Oz. buffer and normal carbine recoil spring, unsuppressed this functioned the .278 gr Wolf for one round and eject, could not eject the .245 gr Tula.

Suppressed it ran both types of ammo without issue, I was planning to keep this setup suppressed, so this build needs a few more tweaks but I think I have the setup I want and mag capacity/availability. I ordered 2 more Tubbs recoil springs when I got home, as I will be running the Lightweight buffer and spring in this.

Next test will be mags fired at full capacity for function test suppressed, I am also going to test a linear compensator to see if it will run both types of ammo.

Now for the AR15 9X39



I forgot to mention the old ass red dot BSA sight on the beast above, that thing still works and it has been used on all kinds of guns, even Saiga 12's it sucks but it works.

Key setup parts;

Unknown upper, lower is from the Blackout build in the first pic, and the BCG came from the 9x39 upper from (Pro2ATactical) the lower will change to a billet lower once my Brace comes in.

10.5" 9x39 barrel  .143 gas port opening pistol length .750 Ergo adjustable gas block from (KAK SS I got this used so the gasport may have been opened up by the previous owner)

I started testing this with the Spikes tactical 4 Oz. buffer and normal carbine spring

PWS Gen II compensator 5/8x24 .30 cal opened up to .385

I fired it first unsuppressed using a PWS .30 cal 5/8x24 compensator which I bored out to .385 to clear the 9mm round.  this would function the .278gr wolf for 1 round but not a second. The .245gr Tula would fire and eject but barely clear the side of the gun.  

I spent considerable more ammo trying to test this with the 3 mags I brought.

Next I used a Navy style tri-lug adapter from (In Lead We Trust) to adapt from the 5/8x24 to 1/2x28 with a 9mm through put so I could use my 9mm suppressor.  This worked great and all rounds fired and functioned.    

I did load 8 rnds of the TULA .245 gr into the AR Stoner mag #1, First 2 rounds loaded and fired third did not load.  I reseated the rounds in the mag and it fired 2 more then, no load. The last 4 rounds fired without issue.  I then loaded 5 of the .278 gr Wolf first rnd fired, no load, reseated the rounds in the mag and the 4 ran without issue.



AR stoner 6.5 Grendel mag #2 would not load from the right with 4 rnds and actually not all.  How I reshaped the follower and bulging caused this, so low on ammo I did not use this anymore in the testing.



I then loaded 10 rounds of .245 gr Tula into my old 20 rnd AR mag 4 rnds went without issue then fail to feed, reseated rnds in the mag and the rest fired without issue.  Then i loaded 8 rnds of the .278 gr Wolf and they all fired without issue.




Next I took the Spikes Tactical 4 Oz. buffer and normal carbine recoil spring out and put in the Tubbs lightweight buffer and flat wire recoil spring, surprisingly unsuppressed this functioned the .278 gr Wolf for the  3 rounds I put in the AR Stoner 6.5 mag and I then loaded 5 rnds of .245 gr Tula they ran without issue.

I was getting excited at this point, as I wanted this to run unsuppressed even with shit ammo like Tula. I know what you are thinking the round count is low, I got that and this needs more testing but the results today were better than expected.

I knew if it ran unsuppressed, then suppressed would be a no brainer, and it was, with the Light weight buffer and spring this setup ran very well. I continued to load 3-7 rounds in each mag and they were cycling except a few over rides on the AR stoner mag.

I will show pics of the AR stoner mag mods I did, but I don't think the aluminum side walls are strong enough to minimize the bulging, the bulging aspect moves the round down and away from the bolt lug which is needed for loading into the breach.

Next test will be mags fired at full capacity for function testing using only the PWS Gen II COMP, I may test a linear compensator to see if it will run both types of ammo.

Note: About AR mags and loading them with 9x39, the approximate tipping point is at the shoulder of the rnd, and against the false 5.56 bullet mold on the shoulder of the follower, so if you broke off the head of a q-tip and placed it in the back of the mag on the follower and load a round on top of it, this keeps the bullet nose down and the rear of the round up, to be caught by the bolt. Its just a simple test to see how the bullet rides in the mag you are testing.









This is what you want to see

Mags I have tested to find a suitable donor so you don't have to waste money finding out the hard way.

KS-47;

10 rnd Saiga AK74 this loads about 7 rnds, with mods it could work but I only have one so I won't be doing that, How ever I will be modifying a cheap bulgarian 30rnd AK74 mag.
Keep in mind if you mod this mag then you may have over insertion issue if used in the AK74.



9 rounds in this 30 rnd AK74



10 rnd Vepr 6.5 Grendel this fits 10 rnds I did mod this and it would work however the plastic is too weak on the sides and the bulging will not let it be inserted into the KS-47 mag well. 3-4 rnds it will work







AK-47 for get it, its a no go

75 rnd Chinese drum has potential but the grooves for the bullet are made for 7.62 and the 9mm will not work, but they have straighter angle to the mag well than my Russian or Romanian drum mags.

30 rnd Csspec 6.5 Grendel mag, its a no go for 9x39

I think Csspec mags has the right idea and they are 30 rounders, so just make these work for you.

VSSAR-15;

7 rnd Beowulf mag looked promising as the rib toward the front of the mag is flattened a bit, so I was hoping this would resolve the bulging aspect but after 5 rounds it too started bulging, the low round count made it just not worth the effort.





26 rnd AR Stoner 6.5 grendel mag has promise, if it was made of steel it might work better, this needs more testing and mods to the follower to work. I was able to get 20 rnds in one but bulging was significant.

20 rnd Colt black plastic follower mag has been my work horse so far, I have not modified it yet, but if I did I would build up the back end of the follower with glue slightly and it would run reliably.

30 rnd mag sucks after 5 rnds, bulging gets bad fast, bullet nose goes up and ass end of round goes down it will not feed rounds at that point, how ever I have a box of green followers and I plan to play around with those to see what is possible.


I have some other ones I am going to check possibility with, but for now I hope this helps others.

I'm waiting for a light weight buffer to come in then I should have it ready to test again, with the changes I made.  This is the version that has the 10.5" SS KAK barrel, I just finished it off with an old Hogue front end I had which sort of gives it the VSS look.  I got this lower and put the pistol tube on it to complete the pistol lower, it has the flat wire recoil spring in it now, and I changed the gas block from an adjustable to a standard. Once the buffer comes I can test it out for function.  I would like to find some of the D&H 9x39 mags.



Here it is under the hood

I could not find much info on if a Fostech echo II will work in the KS-47, there is a video so I know one working with it.
If you are looking to do this I found issue, inside the trigger control parts well of the receiver you will find part of the mag catch spring sticking through.  This will not allow the fostech trigger works to drop in and line up with the axis pins.
This means you will have to cut a notch in the fostech echo II trigger housing, OMG that is sooo expensive! Well yes it is but this is merica and I make what I want.

You will need to notch it as my picture should explain it, I have not had a chance to test with live rounds but the function check works.

BTW my light weight buffer came in....huh not so light weight, or at least not so light enough for my needs.  I busted it open and dumped the unneeded weight, threw in a spring to keep it rigid a bit, it should work.
Another note the KS-47 actions do not seem as smooth as the AR-15 actions, maybe it is the buffer tubes I am using, or a combination of the tubes and the flatwire recoil springs.  My AR-15's are smooth as butter and take little effort to pull back, the KS-47 seems gritting and takes more effort, does anyone have this issue?

I tested out the 9x39 AR variant as I said I modified the buffer and it ran both .278gr wolf and .245gr tula unsuppressed with no problem.  The problems came from my mags, the colt 20 rnd mag works awesome but only holds 10 rnds, my #1 6.5 grendel mag I modified would run 8 rounds well but still a few hiccups.  The setup I have is good but mags are a problem at the moment, I will keep searching for a better solution.

The KS-47 needs some polishing but it ran both ammo types great suppressed.  The Csspec mags need a few more tweaks but they will work once the tweaks are worked in.  I tried to run it unsuppressed and it would run 2 or 3 in row then be under gassed.  The .278 runs better where the Tula just doesn't have enough poop to work.
I might open the gas port hole a little more and see if it will run unsuppressed.

Overall I am really happy with how the AR version functions, it is a blast to shoot.

I ordered a couple 6.8 mags, one is a 28 round and the other was a 10 rnd, the 10 rnd is an ACS mag which will not work with 10 rnds of 9x39. 7 rnds seem like they will work, but need a live fire test.

The 6.8, 28 rnd looks to be very promising, I loaded 23 rnds and it seems not to budge very much, Its a duramag. I hope I have time to test it out this weekend if it runs well then I will get more.

there was a guy on here about a year ago who bought a 3d printer and made a follower to get it to feed good from some AR variant mag. May search him out.

Found it https://www.ar15.com/forums/ar-15/-ARCHIVED-THREAD-Comrade-ARFCOMMERs-new-9x39-AR-build/121-743618/?

And did some more digging and found his screen name in an old PM H4ppyB34r      @H4ppyB34r You still working on this project?

Good info thanks, looking at and loading this 6.8 mag I really think it will work well, between the 2 mags I bought, the duramag has a front rib that is very shallow.  Which is perfect for this round, I have high hopes this will work.  Thanks

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22 RNDS LOADED IN THIS MAG
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For anyone following along I have not had a chance to get to the range, but hopefully this weekend I might get some time to do so.  I ma still trying to find better feeding options so the search continues.

The dura mag worked great, I ran 22 rounds with no issues, then 2 sets of 20 rnds and last 25rnds all with 100% reliability using a combo of wolf and Tula.

I have not had a chance to get back to this as I get side tracked on other projects all the time.  I did order more of the DURAmags and I will be testing all of them and if they work well, I will try them with a binary trigger.  I do love how this gun is running, I put a different red dot on it Romeo5 so I need to sight that is as well.

Duramag 762 x 39 work flawless in all 3 of my 9 x 39.

right on

Try a lighter spring. I use a sprinco yellow (RP) spring and an H1 buffer. Also, I stretched the mag spring about 3/4"

I have both of mine running well with my spring and BCG setup but I will keep your ideas in mind.

Stretching the spring, did this give you a little more tension against the feed lips?

Ammo just went full retard so I a, looking at loading options, what do you guys use for projectiles?

270gr Speer Hot-Cor

I have been buying them for a little while

Haven't actually reloded yet, but have most of the components

https://www.google.com/amp/s/thisguysguns.wordpress.com/2020/01/23/reloading-9x39mm/amp/

This will be a good start

thanks

I am glad I saved my brass cased Yugo ammo from years ago, I knew it would come in handy some day.

Awesome news, I found a fight lite SCR at great price, and did a good trade deal on a 6.5" inch 9x39 barrel and some D&H mags.  While I am waiting for the SCR to come in, I will be building the new 9x39 upper to swap onto the SCR this should be sick! I am pretty stoked.  I can put my suppressor on this and will be awesome I hope. I will post pics once it is all together.

my next 9x39 project, this is the canvas