Joe C,
Sorry, my post was not specific. The mg/ml is a weight per unit volume. The weight/unit volume will be on the bottle. A cc does equal a ml, but the weight in mg of deca (or whatever) contained in that cc will vary. Assuming that the bottles are what they say they are:
100mg/ml of whatever requires 3 cc's to equal 300 mg.
150 mg/ml of whatever requires 2cc's to equal 300 mg.
300 mg/ml of whatever requires 1 cc to equal 300 mg.
Andy13, you are right, what I posted was not helpful. I understand the Physics. Still working on the Chemistry, that's why I'm here. And, if this post is wrong, you guys need to tear me a new asshole as I have no business messing with gear!