The majority of reloading issues are centered around a swelled case or bullet profile engaging the leads. We can use one reamer to open the chamber and another to taper the leads. We drop the cartridge into the modified chamber to verify fit (head space).
There you have it, a perfect fit for your home rolled cartridge..... (that nobody else can duplicate). We don't mind providing this service for our customers but as I have pointed out previously, it can create problems when the same barrel enters the used market.