I was wondering if anyone shots a mossburg 535 slug gun and if so
what slug do you recommend shooting out of it?

does your 535 have a rifled barrel or smoothbore barrel? Shotguns are very iffy when it comes to ammo, for the 12ga stick with a 2-3/4" shell, you should try various ammo, if it's rifled, it seems the Lightfields work great out of most shotguns

It is rifled

Lightfield slugs always shoot good

the reason the Lightfields seem to shoot well in all shotguns is the fact the sabot expands allowing all the pressure to stay behind the sabot. Now these slugs hit hard, fly good, the downsize is, at 100 yds. they tend to drop fast....If you like how these fly, at 50 yds., you want to be about 2.5" high above center, this should put you out to about 125 yds

Is that the 20 ga bolt action?
Or was that a savage I'm thinking of?

The 20ga bolt action is the Savage model # 220f

browtine 7 has a Mossberg 535, a pump action 12ga

The most accurate slugs I have found for my HR are the 3 inch Winchester slugs that have a saboted .50 cal bullet. They group less than an inch at 50 yards and only about an inch and a half at 100. Don't know if they would group in a Mossberg but they sure do in my Ultra-Slug Hunter. And they will untrack a whitetail in a hurry!

I have the 500 in the Trophy slugster Crown Grade in both 20 and 12ga. The 20 LOVES Federal Barnes Expanders 3". The 12ga really likes the old ACTIV 1oz 2-3/4", punkin ball with chandelier attached wad. Both are rifled barrels and the proto type of the 535. Ported barrels.

I have a Mossberg 535. My brother recommended Winchester Partition Gold. I liked them. Then I found the Winchester Dual Bond. These are fast with minimal drop, especially the Dual Bond. It is all I shoot. They don't go far.