Not into chainsaws but did spend some time on the sales counter at a local marine repair shop in my misspent youth and we sold parts for just about anything that could be classified as a small motor. The boss bought Oregon Chain in bulk on bobbins and we made saw chains to spec for customers. Nasty stuff to work with; easy to get nicked or slashed, vary sharp. Most of the back room crew were Finns, that is Finnish. Spoke the language and had the accent. Knew their stuff. Think the old owner is either dead or in a home somwhere. The kids took over when he retired but the mother had issues and debts............
I spin my own chains. The breaker and spinner weren't all that expensive and chainsaw chain is significantly cheaper in bulk.