Tight barrel release is caused by several things. If it does it on an unfired gun, you can lap the shelf and latch with a mild abrasive, I've used Flitz, it you want something more agressive, valve grinding compound will work much faster, but use it very sparingly and only work the button a few times, then clean it off and test. If after firing, it's usually caused by poor latch engagement or too hot a load. I've also seen some different colored latch springs that are heavier than normal, they have a redish tint instead of the normal brownish or metallic color, these are on late Gardner made frames, it's possible they've taken some hints from discussions here and improved the latch spring strength in the last few years.
Tim
