I bought one. Someone else had built it on a Special Weapons receiver. The receiver was nice, but the upper was all hacked up to make the AK mags fit.
I HAD LOTS OF FEEDING PROBLEMS.
When I pull the trigger, the rifle has to fire and be ready to fire again, providing the mag is not empty. My AR47 was ready about 10% of the time. The other times, I had to pull the charging handle back, or release the mag and clear a misfed round, etc.
The seller said that maybe it was my choice of AK mags, and that he had less problems with Hungarian 20 rounders. Needless to say, I sent it back and he was honorable enough to give me a refund.
So, maybe if Special Weapons makes an upper that is designed for the lower, and a bolt carrier also, then you will be less likely to have problems. Or, if your smitty is really good. But if you get one that went through a questionable smitty...
I took that money and bought an Aresenal Inc. AK variant. IT IS AWESOME. It is almost as accurate as my Colt 20" AR, and NEVER HAS FEEDING PROBLEMS, regardless of whether it is clean, or hot, or whether or not I use supercheap ammo.