Well guys, after getting your advice, I bought the Federal Heavyweight #7's (on sale at Cheaper than Dirt, thanks!) and the Rem SF choke (for $10 from Midwest gun works, thanks again!). I had my gunsmith drill and tap my new 870 youth 20 gauge, and put an EGW base on it. The old Aimpoint 9000 SC went on top of it... Two light 2 3/4" shells and she was sighted in, then followed up with 2 of the HW#7 loads to fine tune it.
Finally connected this morning. Shot a tom in full strut at exactly 40 paces. He was facing right toward me and getting nervous about the hen decoy that wasn't coming to him...
The shot flipped him over backwards. Man, does that HW work! Broke his right wingbone and also his leg. He just went DOWN. Flapped a few times and it was over. I'm thinking the HW#7 "might" be good at further than 40 yards!