I used Jim's products and followed the instructions that Katherine provided above.
I can't recall if I used low or high on the heat gun. I believe low. Like Katherine said keep the heat gun moving. You will see the color change.
For reference, here are a few pics of mine.
After both products were applied and prior to heat....I did a coat of tannic and a coat of iron nitrate. Looking back I could probably been heavier on them..
After heat....Notice the cherry color...
I then used Chamber's oil and scotchbrite to rub it back. I believe I used green but possibly the blue "non-scratch" stuff. I do believe it was the normal green stuff though...
I wasn't going for any kind of "look". I accidentally rubbed a little too hard on the cheek piece and about cried. After thinking it out, I rubbed out the cheek piece, grip area and forearm area to give it a worn look. I didn't touch the lock area and edge of the buttplate etc so I didn't run those area back as much..Left a nice dark look to those areas...
For my first attempt I found it very easy to work with and I like what I achieved.
I'm no pro....That's my first attempt.