A permanent solution would be to cut a thin price of plastic (like the type that a lot of stuff is sold in these days, "bubble packages" they call em)
And glue it in place as a shim and call it a day. If you have been using metal mags wear could be an issue. The mag catch could be rounded at the top just enough to allow the mag to start moving it out of the way. But yeah if the tape works then a plastic shim is likely gonna do ya just fine. Also as was stated above, airsoft, paticularly if you stick to the mid and low ranged stuff, will more often than not require a bit of tweaking to get it running smoothly, weather it be an issue like yours or some hop up mods and compression improvements, down to filing and grinding to make parts fit (rails grips etc..)
Buying higher end usually fit and finish are nice, but often the hop and compression systems still need a bit of love. Gas is about the same, some love and lube (yeah I said that) and some tweaking are often needed. As for bolt actions don't even get me going. 500+ for a rifle and 800+ for parts to make it gameable lol.
Hopefully the shim will solve your issue
