In reference to magazines for the Colt [AR-15  chambered in] 7.62×39 [,the AK-47’s cartridge.] Have you had any experience or feedback with the ones that have the AK  type mag. welded to the top of an AR type mag.? I think they call them Frankenmags? Thank you, – Tom
JWR Replies: Because of the sharp angular transition between the curved Kalashnikov magazine and the straight AR-15 magazine well, they don’t work very well at all. You can expect lots of “failure to feed” jams. The sadly inescapable problem is that the 7.62×39 Russian cartridge uses a steeply tapered case, designed specifically to feed in a curved magazine. AR-15s should have never been adapted to fire this cartridge. It was a very bad idea! If you load more than about 10 of these cartridges into a straight magazine, they tend to get jammed, even to the point of “tipping over” in the magazine!
I recommend that you sell that 7.62×39 upper receiver group (or perhaps the whole rifle) and buy an AK or SKS. (Or better yet, a Valmet  M62 if you can afford one.) For the now “surplus” AR-15 lower, (assuming that you want to keep it) either get a 5.56mm NATO upper receiver group, of if you want more “punch” then get a 6.8mm upper. (See the recent discussion about these in SurvivalBlog, posted on November 4th .)