My Rifle Dynamics 74 feeds Russian and Bulgarian mags flawlessly (and even magpul). Thousands of rounds at rapid fire, slow fire, mags going in and out, slapped to the ground, reload, insert, and I still have had nothing but perfect performance. I put a new AIMS 74 mag in and every third or so round, a stovepipe.  The round sticking out, bullet first, jammed against the chamber by the bolt.  I looked as closely as I can and see no design reason why this is happening.  They're Warsaw.  They seem to sit the same in the rifle.  The bolt runs through with no bind.  I don't get it.  I have snap caps coming tomorrow to see if they are kicked up differently than Russian or Bulgarian mags.  What could it be?  If you have experience, please share.  Thanks

Update: cycled the snapcaps slowly by hand, quickly with the recoil spring in; no problems.  Watched the dummy round feed from the Romy mags and from a Russian mag, no difference.  Conclusion: no idea.  I'll shoot em again.

Okay, I went back to the range with both Aims 74 mags.  I labeled them 1 and 2.  Loaded both with 15 rounds and both performed as they should.  Loaded both with 30 and number one started acting up.  Not loading a round after first shot.  Then I charged it and it fired but fed the next round sideways sticking out of the right side of the rifle.  Just like before.  I pulled that mag out and loaded number 2.  Slow fire was fine.  Rapid fire was fine, and super rapid fire...all as it should be.  Perfect.  Mag 2 is good to go.
So, under mag compression in mag 1, the rounds won't feed.  I think they are under resistance under the feed lips and the spring isn't strong enough to force them up.  So I'm gonna look at Wolff and get a new mag spring.  It's all I can think of.  It isn't a difference in mag geometry because the other one feeds and number one feeds with 15.  Must be that extra tension under the steel feed lips.  I'll also look tomorrow for burrs or hangups.  
After I got zero replies here, I thought, "anomaly, don't give up on the mags."  So your silence was helpful. Only in the AK forum can we say that.  Silence = deference to the AK design.  You can quote me.

It is a little slow here lately. There is not much new in the way of AK magazines at the moment.

I think the true Romanian 74 mags have a (very) slightly different spec than some of the other countries 74 mags. I say this because I have 3 Romanian SAR2 rifles and several 74 mags either don’t fit or fit very tightly. I’ve noticed most, but not all, Bulgarian polymer mags and Magpul 74 mags butt up against the center support cross bar that sits just behind the mag well. The Romanian steel mags, bakelite74s, Tapco74s(go figure??), and a small number of my Bulgy74s do fit. I think the Romanian spec is that the center support is literally a 1/2 mm or so farther forward than some other countries AK74 designs. Thus, the Romanian steel 74 mags have just a hair less material on their upper “back side”, just above the rear locking lug. That said, I wonder if the problem might be related, to a degree, to the very slightly different dimension of the Romy mags.

Maybe.  But the other one cycles fine.  I just don't know.  I thought that the inside of the feed lips might be rough and the rounds aren't cleanly being stripped under full load pressure, so I dremmel sanded the inside a little to remove any burrs or inconsistencies.  I'll work with it, it cost enough $.  I loaded a Russian mag and looked and looked, then a Romy mag and looked and looked and although I don't have a calibrated eye, I couldn't see any difference in clearances or how the round was stripped.  Dummy rounds cycled fine.  It's that full load in that one mag... I'm either going to figure it out or I have a paper weight.  
Thanks.  Again, glad to see this is a rare occurrence.  I think it can be remedied

It might be just an issue w/ that particular mag. I would add, in reference to my previous post about the AIMS mag maybe having slightly different dimensions, I haven’t actually used my steel AIMS mags in any of my other 5.45 rifles outside of the Romanian SAR2s...I’ve never had an issue with them but, I haven’t tried them in a non-Romy rifle either.

Wolff spring on the way... I'll update

Curious to know if the new spring fixed the failure to feed mag?