Your titles are a bit confusing.
The thread title refers to AK mags, but the actual poll refers to "semi auto magazines".
Since I'm not sure exactly what the poll is asking, I didn't vote.
I've never had any problems with AK mags being kept loaded for years, this includes 8 or 10 Tapco 30 round mags that've been loaded continuously for the past 4 or 5 years.
I have steel AK mags from various places such as China, Romania, Russia, Yugoslavia, East Germany and even some South Korean commercial models. Some of these mags have been loaded for 15 years, but I've never had one fail to work when I used them.
My luck has been mixed with M-16 pattern mags.
My 30 to 40 year old Colt and Adventureline mags have been loaded for decades and are still in perfect working order. A bunch of much newer Cooper Industries and Sanchez GI aluminum mags had the feed lips spread apart after 3 or 4 years loaded, they still work, but I no longer keep them loaded, nor would I trust them for serious use.
I had even worse luck with the plastic Orlite mags, four out of seven had at least one of their feed lips crack completely off after being loaded for a couple of years. In their defense, these were Israeli surplus mags that had probably led long, hard lives before I got them.
I have 3 of the telescoping 30/45 round Thermold magazines that have been loaded since the late 80's. With the exception of one that fell off of the top shelf in the safe and landed on its feed lips which caused it to split up the back, they all work fine. Even the split mag works OK if you hold the feed lips together when you insert it.
