Quote Originally Posted by Throbert McGee View Post
I was taught to pronounce the Russian "hard L" as a little bit more dentalized than the English "L" (which is theoretically "alveolar"), but it's quite possible that I dentalize the hard L too much when trying to speak Russian.
That's correct, the tip of the tongue touches the inner surface of upper teeth when pronouncing the Russian hard "L".
I've never heard your pronunciation, but as to me, I doubt you can "dentalize it too much"

Quote Originally Posted by Throbert McGee View Post
However, to my ears, the difference between "alveolar" and "dental" is more subtle than "hard" vs. "soft."
Agree.

Quote Originally Posted by Throbert McGee View Post
But it's possible that a Russian with very good ears might think that Americans don't make the "hard L" hard enough?
Yes. And one does not need to have "very good ears" for that. When I heard Russian pronunciation of some Americans, I always noticed their "L" sounded "semi-soft" to me when followed by a vowel. A word-final "L" is usually OK, but vowels somehow affect it more.
The reason for that is the Russian "hard L" is velarized which strengthens the contrast with its soft counterpart. And Russians sub-consciously hear it "soft" when it is not velarized. That's what happens to French, German, Spanish, Italian L's: they are neither palatalized nor velarized, which makes Russians perceive them as "soft".

I've just tried to pronounce the velarized Russian "hard L" using the alveolar tongue position, and I'd say it is physically possible, but very difficult. It is hard to keep the correct "spoon-like" shape of the tongue of the velarized L with the alveolar tip position.