3.5 in buckshot?
 

do you guys know of ant 3.5 inch buckshot that is factory loaded and 00 or bigger for 12 gauge

Midwayusa has some.

----> http://www.midwayusa.com/browse/Brow...***9217***9488***

There are lots of choices out there. Several guys I hunt with use the Winchester 3.5" High Velocity 00 buckshot. I've tried it when I used a 3.5" gun but preferred the way the 3" 000 Winchester buckshot shot and also the Federal Flight Control stuff. Several of them have switched to the Federal Flight Control stuff. I just don't see the advantage to 3.5" shells for buckshot. It's never shot as well when I've tried it and it kicks way too hard.

Or Bigger?
 

Type Dixie Slugs or Dixie Tri-Ball into your search engine. Dixie has some of the biggest tight patterning buckshot rounds made.
How about three 3/4th ounce .60 caliber pellets and less than 6" patterns at 40 yards from full choke 12 bores with full chokes.