Go with the K100, I am anxious to hear a good test report on one as no one ever really talks about them. The M77B is bulletproof, one of mine now has around 3300 rounds through it, never had a malf. of any kind and eats every kind of ammo (except lead, lead would make it explode). I let it go nearly 600 rounds without cleaning or lubing and it just kept working. The only downside to the pistol is the cheap ass weak plastic grips that chip.