Once my obsession turned toward Civil War artillery, I got some excellent references on field pieces, especially those related to the Battle of Gettysburg. A big part of the reading was to figure out what purpose all the parts on the cannons played, and that led to comparing them with the parts issued with the Sideshow Civil War pieces. I am indebted to member WestBatman for pointing me in the right direction and advising me on what needed fixing. He was actually instrumental in advising Sideshow and providing them with technical references. Here are some of the changes I've made on each of the pieces they produced.
The biggest problem I saw was with the hand spikes. The hand spike was carried on the side of the cannon and used at the back to move the trail from side to side as the gunner aimed - a simple lever so one man could make small adjustments. Too many times they seem to have been used as weapons of last resort when the guns were being overrun. Unfortunately, the SST version was puny and without the ring to hang it on the carriage. AND they only provided one when two were issued. I made new hand spikes from dowels. I don't have a lathe, so I chocked them into an old hand drill in a vice, and used a block sander to taper them down. They still aren't thick enough, but anything thicker wouldn't fit in the D-rings on the cannon. A ring was added with a small cotter pin.
The rammer/sponge were also small, and there should also have been two, and the worm was very thin. BattleGear makes a nice worm, and I made the rammers from dowels, with a copper band around the rammer head. The sponge was made form some "sheepskin" from some Christmas ornament sheep. Two were made for each cannon, plus some short versions were made to show them in use. I drilled a small hole inside the muzzle end of the barrel to fit the dowel into.
On the trail is a heavy rope called the prolonge. It was used to pull the cannon without hooking it directly to the limber, and this was called "retreat by prolonge". Either the horses or, in some cases, the men would pull the cannon backwards as the crew continued to fire at the oncoming enemy. Sideshow used some thin twine with tiny hardware, and this was replaced with heavier cord and jewelry hardware from Michael's.
The last change I'm making is with the lock chain on the side of the carriage. This was used to lock the wheel when the cannon was parked - NOT when it was being fired. (The cannon had to be free to roll back from the recoil, or the force would eventually tear the barrel off the carriage.) The puny chain was replaced with the heaviest i could find that still matched. It should be a bit larger, but is still better. I took photos at Gettysburg to make the proper locking mechanism from some links and some flattened wire.