Evil Monkey said:
What's up with these G3 clones and CETME's not having the regular magazine catch lever like the AK?
Blame it on BATFE. The G3 has a proper paddle-style mag release, almost identical to the one used on the AK. Unfortunately, the pin that retains the paddle also connects the lower receiver to the upper. It's the lower that holds the FCG, or course, but unlike the AR platform, the upper receiver is the "firearm" under US law.
The result is that at one time you could legally import or buy a semiauto version of the G3, and separately buy a full auto (or select fire) FCG, and the full auto parts would simply drop in. That's not kosher under U.S. law. So the BATFE mandated that any G3 type rifle (at the time, the only one was the H&K model 91) had to have the upper modified in a way that made it impossible to attach a full auto lower. The way H&K accomplished this was to remove the pin that retains the lower and replace it with a ledge. Semiauto lowers now "clip" onto the ledge on semiauto upper, and full auto FCG parts won't fit in a semiauto lower.
A side effect of removing that pin and replacing it with a ledge is that the paddle mag release now had nothing to retain it. H&K took the cheap and easy engineering solution of just substituting a push button. As you've noted, it is an ergonomic nightmare.
You can have a paddle mag release installed on a PTR-91, HK 91 or CETME, but it's expensive. The parts and work, including refinishing, will run $200-300. As iamkris noted, the Tac-Latch is a less expensive drop-in alternative, and I have one on my PTR-91. The last I looked, a Tac-Latch sold for around $40. The paddle on a Tac-Latch moves side-to-side instead of back-to-front, but it does make mag changes a lot quicker and easier than the stock push button, and it's a lot less expensive than a true paddle mag conversion.
The PTR is a fine firearm and the heavy barrel also makes a very nice fireplace poker 
