Use to be a issue long ago. Not so much any more. Whats the ring end gap at BDC, 1/2 stroke and TDC? Keeping the ring end gap on the tight side of spec will keep the pin in place. Also the off chance that a big exhaust port may not help also. When hot the ring may push out on ex side, that opens ring pin side. Pin ends up in intake/reed then on piston.