IMHO you have two choices --
Federal Flight control - if you can find them in stock and want to spend somewhere between $1.50 and $2 a round.
Or
Buy some basic OO buckshot and shoot a few test patterns with your gun to test and see what works.
I took the second option - I paid $.65 a round (including tax & shipping) for 25 round boxes of S&B OO buckshot
I am happy with the pattern so that is what I am using.
In my situation I will not be making long shots with my HD shotgun - and if I had to I could always pull a slug or two off the side saddle -
I think any of the loads I tested would get the job done - and when each trigger pull costs me $.65 I don't mind blasting away at the range - for $2 a trigger pull not so much.
Sure someone can say - isn't your life worth a few extra $$?
I would just say I have confidence if I shoot someone inside my home with the S&B OO buckshot they are going to be just as "stop the threat" as if I had shot them with Federal Flight control or any other high end shell.
I think the high end shells have an advantage if you needed to make a shot if someone was holding your wife hostage - so if you are concerned that is a possibility maybe the upgrade would be worth it.
YMMV