The bolt idea would be good but the pin is quite small diameter, less than 1/8 inch.
I owned a rifle very similar to this one in 1976, but it had a large brass screw on either side of the forend, those worked better but as I recall they also kept coming unscrewed.
I think the idea for the pin was borrowed from rifles that had wooden forends, but those were much lighter in weight and had a lot more friction against the barrel to help hold them when the gun recoiled.
Ah me. And it is such a nice rifle in every other way. -Ken