I'm working from memory here, but I seem to remember reading in '72(?) they changed a few things in the design...shape of the hammer and if I'm not mistaken the lips on the magazine. I believe they made them a little shorter. If you have an early model pistol with a later model magazine or vice versa that could be the problem. I have a '75 with both types of magazines and have had zero issues with them at the range. I also changed out the recoil spring with the heavier Wolff 22# and it's less snappy. I also changed out the main spring, it'll make the DA lighter...but it's still a heavy pull. You just don't need two fingers for it.
These are great little guns and extremely reliable...not to mention a price that can't be beat for the quality and features. I carry mine in warm weather since its easy to conceal.