Mossberg website only says:

All our choke tubes are marked with the construction designation as a guide. Patterns can vary depending on ammunition brand, load, and shot size.
Slugs may be fired through choke tubes except those with X-Full constrictions or designated "Turkey tubes". Generally, open choke tube constrictions will produce more consistently accurate groups. The "Improved Cylinder" tube is a popular choice for slug shooting.

When they list the chokes, the only one ( and it is stamped into the choke tube also ) is the Ultra full. It say LEAD SHOT ONLY. All other just say what the choke is.
Is buckshot considered lead shot?
I was thinking of going with the 3 1/2" shells for more pellets and pattern the gun with different brands, size and chokes.
I just didn't know if I should shot it through the Ultra Full choke.
Is 3 1/2" sheels less powerful / less range then 3"?
Do they have the same amount of powder with more pellets ( weight ) in which will cut back on range and less knock down power?