I have an old five screw with 4" barrel. The barrel is marked with what appears to be a triangle symbol next to an m resting on its right side, then 38 S&W Special Ctg, and then ending with the same beginning symbol. Patent dates are on top of the barrel. There is no S&W logo stamp on the right side of the frame between grips and trigger guard. The serial number under barrel above push rod and on butt are 300,000 series. The only number on the yoke is 1544 with no dash. Does anyone know anything about this pistol? Is it a real S&W?