On some chains it makes sense: 1/4 pitch carving chain is often .043 gauge, because it is small; 3/4 pitch harvester chain is .122 gauge because it is big.
Others don't make as much sense, such as why STIHL will sell .325 chain with a thicker .063 gauge and 3/8 pitch chain with .050 gauge drivers as defaults on some of their saws. If you look closely, some chains are actually made with thicker drive links that are thinned down at the tangs to fit into smaller gauge bar grooves! There is some speculation that certain manufacturers tried to have unique chain gauges to get you to buy their replacement chains. There might be some historical reason where there were many more gauges that shook out to the 3 most common (.050, .058, .063)?
Years ago, I looked into trying to standardize all of our saws to run the same chains (pitch and gauge), but the cost of replacing all of the bars and sprockets was significant, and some saws reportedly were better performance matched with different chains. It did not make sense for us to do it.
But you might move in that direction as you replace worn out bars, chains, and sprockets, if your saws are compatible with the same pitch chains, and if you can interchange bars, rims, etc. This would be especially helpful if you buy chain in bulk, or can spin down larger, damaged loops to fit smaller bars.
If you are someone who likes to go to the store and buy ready made loops off the shelf, you may find that non-standards loop combinations are harder to find. They can always be made up by a good saw shop, or ordered from a place like Bailey's, but you would need to plan ahead a bit.
Philbert
