I just got a Radical Firearms upper in 7.62x39 and installed onto one of my existing lowers (spikes lower with all milspec parts and magpul stock)
upper came with 7.62x39 bcg
added an optic I had laying around (Primary arms 1-6x24)
also got a couple 30 round ASC 7.62x39 mags
and a couple 10 round C products defense mags from here: https://www.northriverllc.com/

modifications I did to the rifle and mags:
dremel the front of the mags for more clearance (C products defense mags work better for me)
widen the feed ramps and smooth the sharp edges with dremel
enhanced firing pin (came with the assembled radical firearms upper)
wolf stronger firing spring
stronger buffer spring (JP enterprises chrome silicon spring)
Ambidextrous charging handle
Spikes T2 buffer (4 oz.)

went to the range Friday to test it with the cpd mag and the asc mag and 80 rounds total of tula hp (40 rounds) AE brass case fmj (20 rounds), and wolf up ammo (20 rounds) and got about 5 ftf, 4 of which were from AE brass cased ammo, 1 was from tula ammo
the ftf wouldn't fully chamber, they almost did but was smashed against the side of the chamber and the bolt was stuck, hard to pull back
the times it would chamber it did fire, so firing pin was not a problem.  the upper I got came with the upgraded firing pin
the only problem was the ftf, otherwise it functioned
it was pretty accurate, although my priority was not accuracy on that day, it was more of a function test with different ammo and unmodified mags
this the group I got after I zero'd the optic.  again wasn't really taking my time so accuracy will get better as I take time for accuracy

after getting 4 ftf with the AE brass, and 1 from tula, I concluded that my rifle doesn't like AE brass and I need to dremel the front of the mags so the front lip of the mags are lower
been doing some research and this is a common problem for these mags.  seems like the round hits the front lip as its getting chambered
so I dremeled 1 mag of each.  the ASC I didn't dremel as much.
so went back the next day to retest with same ammo:  2 boxes tula hp, 1 box wolf hp, 1 box AE fmj brass.  total 80 rounds
this time only 1 ftf from the AE brass again out of the ASC mag which I didn't dremel as much
so now I will dremel more off the ASC mag, and get ready for more CPD mags that I ordered.  the CPD mag seems to work now that its dremeled down some
here's a couple of pics comparing both types of mags before and after dremeling:

this is the ASC mag



and this is the C products defense mag

Looks pretty accurate to me so far. I've been researching more about accuracy and negating the flyer on the upper right and a total of 13 shots, that's a mean radius of .485" which equates to 1.80 MOA.

Looks pretty accurate to me so far. I've been researching more about accuracy and negating the flyer on the upper left and a total of 13 shots, that's a mean radius of .485" which equates to 1.80 MOA.

thanks.  that's with all different ammo.  and I wasn't really taking my time.  1.8 MOA, I'll take that.   

Good deal!  Seems like the gun itself was working well/properly.  Hopefully you'll get the mag thing sorted out.  I would hate it if I had to mod things like mags to get them to function reliably.  For ARs, that is easy as there are many proven mag producers.  Seems like the 7.62x39 variety isn't as good in terms of mags as well as finicky uppers.  I've read about their problems as well.

Looks like some decent grouping for what it was (function testing).  Looking forward to seeing how the different ammo performs, particularly brass vs steel.  That and testing the AR upper against your AKs. 

I did some research before buying the upper.  I was aware of most of the shortcomings of the AR 7.62x39, but after weighing the pros and cons, I felt I was up for the challenge.
plus I felt like I'm not really getting another firearm, just an upper to put on a lower.  I've wasted more money on other useless things in the past so what the heck. give a try.
I think of it a learning experience.

I did some research before buying the upper.  I was aware of most of the shortcomings of the AR 7.62x39, but after weighing the pros and cons, I felt I was up for the challenge.
plus I felt like I'm not really getting another firearm, just an upper to put on a lower.  I've wasted more money on other useless things in the past so what the heck. give a try.
I think of it a learning experience.

Not trying to change the subject here. Just want to throw in that I did the same thing with a 9mm upper. Still playing around with it. I am trying different things. But I think I had higher expectations than the upper can provide. So far so good but I think I am not as enthralled with pistol caliber carbines as I thought I would be. Anyway.... 

I have a 556 and a 300BLK upper that I use on my lower. Don't see much need to buy a second lower, especially with the enhanced trigger and all.

next up is widening the feed ramps.  since my only problem is chambering the rounds, I might as well work on the feed ramps.  seems easy enough.

Hehe just take your time.

My advice is to start to widen the bottom portion on the barrel extension first (the extension lug at 6 o'clock position on -- both sides of that lug.). That did the trick for me. I used a Dremel with a cone tip (it feels like a rock like texture- maybe called a sanding stone)  and some flitz. Then polished via cone with cotton like material with more flitz. While polishing I did a motion of vertical motion/  or front to back motion because it seemed correct as that's how a round is chambered. Idk if that made sense.

Good luck bro.

I'm no gunsmith at all, I can only share what has worked with me. Ymmv.

Also when you dremeled the mags, did you do it at an angle? The angle should be smooth on the inside . Imagine if a round is being chambered ... It should be dremeled in the direction the round may ride on the front lip. I wondered why some of my mags were doing excellent and a couple didn't when I first tried and I narrowed it down to me not putting an angle on the few that were hiccuping once Ina while.

Edit: sorry I think we dremeled bout the same . After looking at your pic better. Lol
Also check the dimples on the inside of the wall of the mag . Some times the casing may get stuck. I smoothed those out as well. (The part that the casing gets stuck is where the extractor hooks to extract the casing upon firing, idk the name of that part  but I guess it could be considered the rim ? Yeah I know these are rimless cartridges unlike 357 mag ammo that actually have rims.
I can eject all 20 rounds  from the mag by simply pushing it out by thumb. Like how you would go a glock mag. But it was all trial and error for me , cause I also smoothed out the top lips between the curved part that keeps the bullets in and the front lip by sandpaper only.

Yes. At the end of dremeling the mag I smoothed it from the inside in the angle which ammo would come out. I can push it out by thumb pretty easy. I have the same cone grinder dremel bit and straight ones too. Got some flitz today. Been watching a few YouTube vids also. They demonstrate the technique how you describe basically. Hopefully I get to it this weekend. I got more mags in the mail to work on too. Should keep me busy.
Thanks 

I've had my Palmetto State Armory AR 7.62 x 39 for about two months. Using 10 round C- products mags only. Five different brands of steel cased ammo. No problems at all, none. I liked it so much that I purchased another. Just in case the first one craps out. 

I've had my Palmetto State Armory AR 7.62 x 39 for about two months. Using 10 round C- products mags only. Five different brands of steel cased ammo. No problems at all, none. I liked it so much that I purchased another. Just in case the first one craps out. 

Thanks for letting me shoot it
It's a good shooter. 

I widened the feed ramps. Not by much. Mostly smoothed off the sharp edges. Then polished with flitz.
Cycled 50 rounds with the firing pin out. All fed no problems with the CPD mags 10 and 20 rounders.  I'll try some with the 28 rounders after I dremel those.
The ASC 30 rounders don't feed well at all so I will abandon those. I'm tired of screwing around with those so forget them already.  I'll stick with what works in my rifle.
I'll range test next week.

Stang,

I only got the 20 rounders asc mags (12 total) and 10 rounder (4 total) I also heard the problem with the 30 rounders that's why. Thinking bout stocking up more 20 rounders only because I seen some bad reviews of the 28 but also seen good reviews bout the 28. I guess hit or miss. But it's unanimously "good" with the 20 rounders. If shtf i only plan on SD so 20 rounders is good enough for me. I won't go looking for "war" haha.

Don't quote me on this but try use an actual ak mag spring in the 30 round asc mag. Off hand by my memory, I think that solves the issue with the 30 rounders along with making the middle dimple lower. Some I used a hose crimping tool to push the simple slightly outwards. Then I used a wire brush attachment for my dremel to smooth the crap out of it. Of course it's not completely gone but all has fed good so far. Worth a shot since you have ak's too. No need clip the ak mag spring either iirc.

When I get time I'll try find the vid and re watch it. And let ya know...

My feed ramp..

Yes I've read the reviews on the 28 and 30 rounders
If they don't work then I'll stick with the 10 and 20 rounders
I also seen a vid on crimping the dimple flatter. I think that's the problem with the asc mags getting stuck in the mag
The cpd mags seem to be ok

I scored a couple of the magazine on the left from Daniel over at Kaneohe gun shop a few years ago. He said they were old stock gave them to me cheap I don't know the brand but it works really good!! Never had a failure even after leaving the mag loaded for a few months. Other than that magazine I've always had no problem with my factory colt x39 20rd mags only problem is finding them for sale lol. Asc 28's suck. Lol

How have the ASC 10s and 20s been working ?

And what brand upper are you folks running with what mags?

I picked up a PSA mid-length upper and a few ASC 10 and 20 round mags.

I'll report back on my experience after Junior's baseball season ends and I get a chance to try it out.