I regularly run into researchers who are looking for more precision from yDNA matching than is possible. I often share my own personal experience - which is a bit unusual to dramatically show how misleading it can be to simply count mutations to determine who is more closely related.
Sorenson Labs test
- My Uncle Bob and I are 41/43.
- My Uncle Bob and Richard are 43/43.
- Richard and I are also 41/43
- My Uncle Bob and I are separated by 3 birth events and have 2 mutations of difference (one known to be started by my Father and one started by me)
- Uncle Bob and Richard are separated by at least 24 birth events (we don't know where our paper trails connect) and are a perfect match - no mutations.
Paper trails and mutation count can give very different answers about who is more closely related
- Uncle Bob and I are 36/37
- Uncle Bob and Richard are 36/37
- Richard and I are 35/37
Different marker set - different mutation difference count! Bottom line - use all the info you can gather to assess how men are related and don't assume more than you should. You can use yDNA matching to confirm recent shared ancestry and to get an indication of who is more closely related - but you can't draw firm conclusions on who is more closely related by counting mutations.