Qv deca, like any other vet grade gear is always under filled. Definately get more than you think you will need. Other than that, it is good stuff. Just be sure you know what to look for because there are quite a few fakes floating around.
The holos on the box and vial not reflecting multiple colors (like on a credit card) is the easiest tell. Also, the fakes I've seen pics of have squared corners instead of rounded. For at least one batch of fakes on the holo where it should say "vet vet vet" says "quality vet". When you pull of the holo it should either leave dots, or a V slit; QV is changing to the V, I believe; the fakes aren't attached the same way.
Using 600mg a week here, seems ok.. It's the only time I have used deca so I have nothing to reference it against. The reduced muscle and joint pain properties alone make it worth it's use to me.