296 and H110 are the same powder. Hodgdon doesn't list H110 for 38 Special even in +P loads but does list it for 357 Magnum. The older reloading manuals seem somewhat less conservative than current ones which may explain the use of 296 for 38 Special. Since you're loading for an HD using the older published 296 loads shouldn't be a problem.

That said, I use Titegroup and HP38 for 38 Special even in my HDs.

296/H110 works great in the 22 Jet though and the 300 Blackout too.

Jeff
SWCA #1457