gwsmith:
BEFORE you touch a turnscrew or start messing with the gun, do this:

1) Put in snap caps and close the gun
2) Pull the trigger to fire whatever barrel
3) bump the butt firmly against something like a carpeted floor. Firmly enough to simulate the recoil of a cartridge and reset the inertia trigger.
4) Try to "fire" the second barrel.

If you get a "snap" you're in business. If not, contact Browning.