You need to call Browning.
Not safely
If you see spiral grooves when looking down the barrel, then it is rifled.
Browning did not offer one, but you may find an aftermarket Hastings barrel (www.hastingsbarrels.com) that will do the trick.
Yes. Rifled slugs are intended to be fired through a smoothbore barrel. Sabot slugs are intended to be fired through rifled barrels.
In general, rifled slugs are intended to go through a smooth bore. The twist rates of a rifled slug against a rifled barrel may not agree. If you were trying to get the best out of your rifled barrel I would think that going to a saboted slug would give better performance.
yes.
Any non rifled slug. However for best perfomance you want a "saboted" slug.
Yes
You can, but, it will not be a good thing.
Rifled slugs. Sabot slugs will not be as accurate- hose are meant for rifled barrels.
Shooting rifled slugs is the ONLY way to shoot thru a smoothbore for deer. If you shoot sabot slugs thru a smoothbore, it will not spin and therefore not be accurate. For accuracy, the slug must spin out of the barrel. Either shoot a rifled slug thru a smooth barrel, or shoot a saboted slug thru a rifled barrel.
The only way to know is to experiment with as many different loads as you can find.