Originally Posted by method
Nonsense. Any modern shotgun barrel (and by modern I mean made in the last 100 years) is 'approved' for slugs. They're just big chunks of lead, not nuclear warheads.
Here's a good primer on shotguns and chokes and slugs... http://en.wikipedia.org/wiki/Shotgun
You can't use them in the Mossberg 835 and 935 because they use an overbored barrel
From the Mossberg website:
Can I fire slugs through my 935™ or 835® vent rib, Accu-Mag® choke tube barrel?
No, 935™ and 835® field barrels (those with a ventilated rib) are "overbored," and the extra inside diameter may cause the projectile to "wobble" producing unreliable accuracy. A projectile may wedge inside the barrel causing an obstruction. Obstructions of any kind can cause damage to the firearm resulting in damage to the barrel and/or personal injury to you or those around you. Dedicated fully rifled slug barrels are available for the 935™ and 835® models. Other 935™ and 835® Accu-Mag® choke tube notes: Buckshot and steel-shot loads are not recommended for use with an extra full turkey tube installed.