Only need to change retaining pin if changing firing pin size. Large pin on small firing pin will allow pin to move & can cause action to jam. The length & diameter of the pins are the same, only the hole the firing pin goes thru is different. Firing pin & bolt head need to match in size. Finding a bolt head in, 223 for a 110, may be hard to do. At one time savage made 223 on long action. The shank on long action bolt head is .125'' longer than short action bolt head, this may cause firing pin to not work, if a short action bolt head is used, due to excessive protrusion, some people say they can be adjusted, others use an adapter from Sharp Shooter Supply.