Unable to change arrow item texture and model

So I've only ever seen people wondering how to change the entity, but I was able to do that easily. My problem is the actual item. I copied arrow.json into my texture pack and opened Blockbench to create a new model. In this case, specifically, I changed it into a bullet with a gold block texture (edited to a 2x2 yellow & gold texture). The bullet was cubed like a block as opposed to a normal arrow. When I finished the model I saved it as arrow.json and made sure it replaced the old arrow.json in my texture pack folder. I know it did because when I registered the pack and tested it, the arrows changed to an unloaded texture block (the black and purple one). If anyone knows where I went wrong or if it's even possible to change arrow item models I'd greatly appreciate it.