I had read that someone here had fabricated a full length recoil spring guide rod from a 4" door hinge pin. As one that is always on the lookout for inexpensive, but effective ideas, I had to check this one out. I remember the OP said he had to buy a complete 4" hinge at his local Lowes in order to get the suitable pin. Not at mine! They sell a four pack of just the 4" pins. They were in a satin nickel finish or brass. The brass did look to be simply a gold color plating, but I did not have a magnet with me to check. Since the price was right, I grabbed a pack of the nickel pins.
I turned down the head of the pin to .390 and trimmed the overall length to 3.955" I added a slight bevel on the muzzle end to get it through the spring plug easily, as this is a tight fit as to length. Seems to work fine! If this interests anyone, the pins are made by Gate House. The part number is 0308899. The price for the pack of pins was a "bubba" licous $1.47.