the chain on my husqvarna 460 rancher keeps coming loose no matter how tight i get it, am i doing something wrong?

You're probably not tightening it in the right sequence, or the bar might be worn. Let's go step-by-step.

1. First, loosen the two bar nuts (the ones that hold the guide bar on) just enough so you can adjust the tension.
2. Lift the tip of the bar up to take up slack in the chain. Using a gloved hand, pull the chain snug around the bar.
3. While holding the bar tip up, tighten the bar nuts finger-tight. The chain should be snug against the bar but still able to be pulled around by hand.
4. Now, fully tighten the bar nuts with the tool, using a criss-cross pattern to ensure even pressure.
5. After tightening, check the tension again. It should have a slight sag on the underside of the bar, but the drive links should not come out of the bar groove.

IF THAT DIDN'T WORK: The drive sprocket or the bar itself could be worn out. Inspect the sprocket for hooked teeth and check the bar groove for excessive wear. A worn bar won't hold chain tension. Also, ensure you're using the correct pitch and gauge chain for your 460 Rancher.

HEADS UP: Always re-check chain tension after the first few minutes of cutting, as a new chain will stretch. Stop the engine completely before adjusting.