Have a MkIII with TacSol top end. Three weeks ago it ran 700-800 rounds with no problems. Wife took it to a Steel match the next weekend and it wouldn't go off. I took it apart and cleaned and inspected everything. Looked good to my untrained eye. Yesterday I ran 3 mags through it, first two mags ran fine then third mag had 2 or 3 rounds not fire. Any ideas? thanks in advance.