Welcome to the board, Leix26.
Like GGaskill said, you can even find some small square head bolts at the local hardware store. This fantasy carriage I made is for an 11-inch barrel, and the studs on the steps are square head bolts I got at Ace. I filed the sides down to make them smaller, and filed the four sides on the top to make four sided pyramids. If you've got "junk bins" like most of the rest of us, you can probably find all kinds of things in there to use on a small carriage. The eyes for the side tackle on this carriage are actually made from two old rifle stock fore-end sling swivels that I shaped with files. Like Double D said, the home-made jewelry sections at hobby stores have some useful stuff. I got the chain and jump rings that hold the cap square keys for this carriage at a Hobby Lobby. That chain is exactly what I was looking for, and I've got the package in front of me: 60'' CABLE CHAIN STERLING SILVER PLATED, and I think the price was something like $3.99. The chain is plated steel and I used Birchwood Casey's Perma-Blue to blacken the plating. The brass sqaure nuts for the brass all thread rod that hold the cheeks to the bed aren't nuts. I looked everywhere, hobby stores, and hardwhere stores, nobody had them. Yeah, you can find them on the net: India - minimum order of 2500, or whatever it was; sure no problem, I'll use the eight I need, and the rest can be buried with me. Those nuts are actually the square bases of brass sights that are used for compound bows in archery; the female thread in the base is the exact size I needed to fit the all thread, so I hacksawed the base filed it smooth, and there were my nuts.
Victor; your right about McMaster Carr (and some other outfits like Reid Supply Co. A Division of Reid Entities, and I've got this huge hard cover book from MSC Industrial Supply Co., called "the big book metalworking, maintenance & MORE") having stuff that would be useful for artillery carriages, but that would probably be for larger scale carriages, because I looked, and I couldn't find eye bolts, or other parts that were small enough to be of use on this carriage.
