Ed,
I had some 5160 from Admiral Steel turn out soft after HT at 30-33 Rc. I posted the problem on the Newbies Arena and got an idea but wanted your input. Came up to 5125F slowly,
soaked 5 min., immediate oil quench in 160F quenching oil, cooled in the oil overnight, draw at 350F for 2 hrs, then two 1 hr. draws, air cooling each time. Rc was 30-33 instead of 58-60. Rockwell tester cal checked OK. Johnny Stout suggested removing the scale and retest, but had same result. Any ideas?

OK, let's examine what went wrong here.......
I'm assuming that the temp in your post is a typo. It reads "5125F". I suspect you meant to type 1525F? Anyway, did you use a magnet to test the critical temp? If not, I suspect that the steel was not to critical when you quenched. Next let's talk about the "soak".....I strongly recommend that you DO NOT soak 5160 or 52100. The element content in these steels is not dense enough to require any soak time. More often than not, you will literally wind up segregating the elements rather than getting everything into solution. (which causes hard and soft spots)
Another situation that I have seen occur is during the tempering. Are you using an oven with a thermometer to check the actual temp? I ask because recently I had an individual with just ther reverse of your problem. His blades were extremely hard and brittle. After getting him to place an thermometer in his oven, we discovered that his controls were 100F off (on the low side) in his oven. If your using a kitchen oven, you must realize that the temp will spike up when the elements/burner kicks on. It is critical that you let a kitchen type oven cycle for at least 1/2 hour before you place a blade in there. That way the temp has a chance to stabilize out, and the heat spikes do not take place.
Finally...........and about the only other thing I can think of.........Did you get a data sheet with the steel? It is possible (but not likely), that you were sent some steel other than 5160. I have dealt with 5160 and 52100 for so long that I can usually tell by the look and feel of the bar, but have ran into a few cases where folks were sent the wrong steel by accident.
In closing, let's go back to the magnet for testing critical temp. Your eyes will sometimes fool you on colors. A temp guage will sometimes be out of adjustment and lie to you. Although it seems such a simple tool, a magnet will never lie. If the steel is not to critical it will be attracted to it, if there is no attraction to the magnet........it's time to get the blade into the quench.

Ed,
I relied on the temp and not the magnet, I'm doing it over again. No data sheet on the HR 5160 bar. It's 1 1/4 x 1/4 x 22' stock with a smooth gray scale and rounded edges, cuts easily with a hacksaw and throws out a LOT of sparks when grinding. This time I'll test with a magnet and quench with no soak. Thanks alot!
Bill

I had a friend a few years back that ordered some 5160 from Admiral. Made the first knife from the 5160 stock and started to heat treat. Turned out they had sent him mild steel instead. They made the order good and didn't charge him for the 20' stick of 5160. All he was out of was his time.

I buy a lot of steel from Admiral and have never had a problem. Seem to be good people.