Fed up of the front nut on the Urika 2 rusting and sticking all the time. common fault it turns out.

anyway, i have the chance of a new one to be made in a better material but i need to do a drawing and give sizes. Anyone know what the front nut size is please. the one that screw on to the mag tube that holds the fore end in place.

Or does anyone have one laying around that is going beggin.

thanks guys