MIKE GEORGE says: Most of the manufacturers and retailers of these products don’t recommend the practice. The products are very good for touching up blemishes, like blacked trigger guards and top levers which get worn through constant handling but – in my experience anyway – they don’t work well on large areas.
I once tried to re-blue a rifle barrel using one of these products, and although the results passed at a distance, close-up the blueing looked blotchy. A professional re-blueing, or re-blacking job will look much better.
However, if the gun is of little value and you want to have a go, be very careful to polish off every bit of the old finish, then pay very careful attention to degreasing the steel. After that, it’s just a matter of following the instructions on the pack
Got a question? Contact: email@example.com or Sporting Gun, PO Box 157, Stamford, Lincolnshire PE9 9FU