What is spring tarring and should I do it?

Spring tarring is applying a thick tar grease to a mainspring to dampen vibration and twang.

It works, but most modern springers shoot smoothest with a light moly or lithium grease film and a properly fitted spring guide instead. Heavy tar attracts dust and can migrate forward to feed dieseling. A common quick fix product is Tune in a Tube, which is applied through a transfer port without disassembly to quiet a noisy spring. Full lube tunes are an advanced job; most owners are better off leaving the factory lube alone unless the gun develops a problem.