Took my 870 to the range today. Second time. I was shooting 2.75" 7/8 oz shot Remington loads. At 25 feet tight pattern, maybe 4". It was easy and fun shooting. Any other load recommendations for home defense?

Sounds like you already found it...

I wouldn't recommend birdshot for home defense - especially the tiny shot used in target loads. Buckshot is the way to go when you're dealing with human-sized threats because it has enough mass & sectional density to reach the important stuff deep inside. Despite what you might have heard, there are actually quite a few good 20ga buckshot loads to choose from. The ideal choice will depend on your anticipated defensive scenarios, and how much recoil you can tolerate. You should also pattern-test any candidates at the ranges you think you may need to use them. If your gun has interchangeable choke tubes, this can give you another degree of freedom for getting the pattern you want.

#4 buckshot (.24-caliber) or #3 buckshot (.25-caliber) are great close-range performers, but they need a certain amount of velocity to penetrate reliably. I'd say look for loads that are running at least 1200 FPS. These loads are generally going to contain at least an ounce of shot, so they'll be stiffer than the 7/8-ounce loads you're shooting now. A 20-pellet #3B load should recoil less than a 24-pellet #4B load, given the same velocity.

A lot of folks recommend 3" #2 buckshot (.27-caliber) loads for 20ga defense, since it gives you more lead and bigger pellets. Those are magnum loads though, and they can kick harder than a 12ga when fired from a lighter 20ga gun.

Rio makes a high-velocity 20ga load containing 9 pellets of #1 buckshot (.30-caliber). Not much lead, and less than half the number of pellets in most other 20ga buckshot shells, but the larger pellets and higher velocity should give you some extra penetration if you think you might need to reach out to longer ranges or through walls or doors. Recoil should be pretty light too, since 9 #1B pellets is a pretty light payload.