My 2005 Alliant reload guide shows 2.1gr. Red dot as being max. charge with 71gr. fmj bullet. OAL is listed at .984" minimum. Small pistol primer used (Remington). My Lyman manual shows 2.5gr. as max. powder charge with everything else remaining the same. I would start at 2.0gr. and work up from there. I also found data for 60gr. hollowpoint bullet if you need it. Hope this helps. Good luck and Happy Shootin'!
If 2.1gn might be MAX, why would you start at 2.0gn? Granted, even a 10% reduction would only take you down to 1.9gn.
I know folks hate to do it, but you can call Alliant and ask them. They almost certainly have unpublished data.
Be careful with those small charge weights, as you are at the point where a 0.2gn difference could have a large effect.