I have a 982 as well - I fit the Magpul fore-end and ran into the same issue, but I got it tapped on with a rubber mallet. I slapped on a Choate extension (which was a bit long, so I cut it down with a pipe-cutter) - works nicely.
Pretty decent guns, the 982s - I ground down the front-sight blade to a nub small enough to fit into the cavity underneath an XS tritium Big Dot sight; it makes a nice upgrade.
I also found that the comb of the stock is way too low to get a decent cheek-weld while using the sights (very common issue when manufacturers add tall rifle-sights but keep the original stock), so I added an Accu-Riser comb raiser (Monte Carlo style); now it fits like a champ.
I dunno, maybe some thoughts for you there.